MCP con FastMCP (2/4): capa de transporte, contexto y resources

MCP con FastMCP (2/4): capa de transporte, contexto y resources

En la primera parte creamos nuestro primer servidor MCP con FastMCP y aprendimos a exponer funciones como tools, filtrarlas por tags y componer servidores. En este capítulo configuramos la **capa de transporte**, controlamos qué argumentos se exponen, accedemos al **contexto** de la petición y creamos nuestro primer **resource**.

⚠️ Este capítulo continúa el código de la parte anterior. Para ejecutarlo necesitas el entorno y el servidor de la Parte 1.

📚 **Esta entrada es parte de la serie _MCP con FastMCP_**, dividida en cuatro capítulos que se leen en orden:

> * Parte 1: Primer servidor y tools

* 👉 **Parte 2: Transporte, contexto y resources**

* Parte 3: Resources avanzados y prompts

* Parte 4: HTTP, autenticación y cliente

Capa de transportelink image 1

Si al servidor MCP no le indicamos la capa de transporte, por defecto se usa stdio. Pero podemos indicárselo mediante el parámetro transport cuando lo ejecutamos

mcp.run(
transport="stdio"
)

Sin embargo, si el cliente y el servidor no están en el mismo ordenador, podemos usar http como capa de transporte

Servidor MCPlink image 2

En el servidor, solo tenemos que indicar que queremos usar http como capa de transporte, el host y el puerto.

mcp.run(
transport="streamable-http",
host="0.0.0.0",
port=8000,
)
	
< > Input
Python
%%writefile gitHub_MCP_server/github_server.py
import httpx
from typing import Optional
from fastmcp import FastMCP
from github import GITHUB_TOKEN, create_github_headers
# Create FastMCP server
mcp = FastMCP(
name="GitHubMCP",
instructions="This server provides tools, resources and prompts to interact with the GitHub API.",
include_tags={"public"},
exclude_tags={"first_issue"}
)
sub_mcp = FastMCP(
name="SubMCP",
)
@mcp.tool(tags={"public", "production"})
async def list_repository_issues(owner: str, repo_name: str) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 10 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=10"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"private", "development"})
async def list_more_repository_issues(owner: str, repo_name: str) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 100 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=100"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"public", "first_issue"})
async def first_repository_issue(owner: str, repo_name: str) -&gt; list[dict]:
"""
Gets the first issue ever created in a GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list containing information about the first issue created
"""
# Get the first issue by sorting by creation date in ascending order
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=all&amp;sort=created&amp;direction=asc&amp;per_page=1"
print(f"Fetching first issue from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No issues found for this repository.")
return [{"message": "No issues found for this repository."}]
first_issue = issues_data[0]
# Create a detailed summary of the first issue
summary = f"#{first_issue.get('number', 'N/A')}: {first_issue.get('title', 'No title')}"
if first_issue.get('comments', 0) &gt; 0:
summary += f" ({first_issue.get('comments')} comments)"
issue_info = {
"number": first_issue.get("number"),
"title": first_issue.get("title"),
"user": first_issue.get("user", {}).get("login"),
"url": first_issue.get("html_url"),
"state": first_issue.get("state"),
"comments": first_issue.get("comments"),
"created_at": first_issue.get("created_at"),
"updated_at": first_issue.get("updated_at"),
"body": first_issue.get("body", "")[:500] + "..." if len(first_issue.get("body", "")) &gt; 500 else first_issue.get("body", ""),
"summary": summary
}
print(f"Found first issue: #{first_issue.get('number')} created on {first_issue.get('created_at')}")
# Add context information
result = {
"repository": f"{owner}/{repo_name}",
"note": "This is the very first issue created in this repository",
"first_issue": issue_info
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@sub_mcp.tool(tags={"public"})
def hello_world() -&gt; str:
"""
Returns a simple greeting.
"""
return "Hello, world!"
mcp.mount("sub_mcp", sub_mcp)
if __name__ == "__main__":
print("DEBUG: Starting FastMCP GitHub server...")
print(f"DEBUG: Server name: {mcp.name}")
# Initialize and run the server, run with uv run client.py http://localhost:8000/mcp
mcp.run(
transport="streamable-http",
host="0.0.0.0",
port=8000,
)
Copied
>_ Output
			
Overwriting gitHub_MCP_server/github_server.py

Cliente MCPlink image 3

En el cliente, lo que hay que cambiar es que antes realizábamos la conexión, pasando el path del servidor (async def connect_to_server(self, server_script_path: str)), mientras que ahora lo hacemos pasándole la URL del servidor (async def connect_to_server(self, server_url: str)).

	
< > Input
Python
%%writefile client_MCP/client.py
import sys
import asyncio
from contextlib import AsyncExitStack
from anthropic import Anthropic
from dotenv import load_dotenv
from fastmcp import Client
# Load environment variables from .env file
load_dotenv()
class FastMCPClient:
"""
FastMCP client that integrates with Claude to process user queries
and use tools exposed by a FastMCP server.
"""
def __init__(self):
"""Initialize the FastMCP client with Anthropic and resource management."""
self.exit_stack = AsyncExitStack()
self.anthropic = Anthropic()
self.client = None
async def connect_to_server(self, server_url: str):
"""
Connect to the specified FastMCP server via HTTP.
Args:
server_url: URL of the HTTP server (e.g., "http://localhost:8000")
"""
print(f"🔗 Connecting to FastMCP HTTP server: {server_url}")
# Create FastMCP client for HTTP connection using SSE transport
self.client = Client(server_url)
# Note: FastMCP Client automatically detects HTTP URLs and uses SSE transport
print("✅ Client created successfully")
async def list_available_tools(self):
"""List available tools in the FastMCP server."""
try:
# Get list of tools from the server using FastMCP context
async with self.client as client:
tools = await client.list_tools()
if tools:
print(f" 🛠️ Available tools ({len(tools)}):")
print("=" * 50)
for tool in tools:
print(f"📋 {tool.name}")
if tool.description:
print(f" Description: {tool.description}")
# Show parameters if available
if hasattr(tool, 'inputSchema') and tool.inputSchema:
if 'properties' in tool.inputSchema:
params = list(tool.inputSchema['properties'].keys())
print(f" Parameters: {', '.join(params)}")
print()
else:
print("⚠️ No tools found in the server")
except Exception as e:
print(f"❌ Error listing tools: {str(e)}")
async def process_query(self, query: str) -&gt; str:
"""
Process a user query, interacting with Claude and FastMCP tools.
Args:
query: User query
Returns:
str: Final processed response
"""
try:
# Use FastMCP context for all operations
async with self.client as client:
# Get available tools
tools_list = await client.list_tools()
# Prepare tools for Claude in correct format
claude_tools = []
for tool in tools_list:
claude_tool = {
"name": tool.name,
"description": tool.description or f"Tool {tool.name}",
"input_schema": tool.inputSchema or {"type": "object", "properties": {}}
}
claude_tools.append(claude_tool)
# Create initial message for Claude
messages = [
{
"role": "user",
"content": query
}
]
# First call to Claude
response = self.anthropic.messages.create(
model="claude-3-5-sonnet-20241022",
max_tokens=6000,
messages=messages,
tools=claude_tools if claude_tools else None
)
# Process Claude's response
response_text = ""
for content_block in response.content:
if content_block.type == "text":
response_text += content_block.text
elif content_block.type == "tool_use":
# Claude wants to use a tool
tool_name = content_block.name
tool_args = content_block.input
tool_call_id = content_block.id
print(f"🔧 Claude wants to use: {tool_name}")
print(f"📝 Arguments: {tool_args}")
try:
# Execute tool on the FastMCP server
tool_result = await client.call_tool(tool_name, tool_args)
print(f"✅ Tool executed successfully")
# Add tool result to the conversation
messages.append({
"role": "assistant",
"content": response.content
})
# Format result for Claude
if tool_result:
# Convert result to string format for Claude
result_content = str(tool_result)
messages.append({
"role": "user",
"content": [{
"type": "tool_result",
"tool_use_id": tool_call_id,
"content": f"Tool result: {result_content}"
}]
})
else:
messages.append({
"role": "user",
"content": [{
"type": "tool_result",
"tool_use_id": tool_call_id,
"content": "Tool executed without response content"
}]
})
# Second call to Claude with the tool result
final_response = self.anthropic.messages.create(
model="claude-3-5-sonnet-20241022",
max_tokens=6000,
messages=messages,
tools=claude_tools if claude_tools else None
)
# Extract text from the final response
for final_content in final_response.content:
if final_content.type == "text":
response_text += final_content.text
except Exception as e:
error_msg = f"❌ Error executing {tool_name}: {str(e)}"
print(error_msg)
response_text += f" {error_msg}"
return response_text
except Exception as e:
error_msg = f"❌ Error processing query: {str(e)}"
print(error_msg)
return error_msg
async def chat_loop(self):
"""
Main chat loop with user interaction.
"""
print(" 🤖 FastMCP HTTP client started. Write 'quit', 'q', 'exit', 'salir' to exit.")
print("💬 You can ask questions about GitHub repositories!")
print("📚 The client can use tools from the FastMCP HTTP server")
print("🌐 Connected via Server-Sent Events (SSE)")
print("-" * 60)
while True:
try:
# Request user input
user_input = input(" 👤 You: ").strip()
if user_input.lower() in ['quit', 'q', 'exit', 'salir']:
print("👋 Bye!")
break
if not user_input:
continue
print(" 🤔 Claude is thinking...")
# Process query
response = await self.process_query(user_input)
# Show response
print(f" 🤖 Claude: {response}")
except KeyboardInterrupt:
print(" 👋 Disconnecting...")
break
except Exception as e:
print(f" ❌ Error in chat: {str(e)}")
continue
async def cleanup(self):
"""Clean up resources and close connections."""
print("🧹 Cleaning up resources...")
# FastMCP Client cleanup is handled automatically by context manager
await self.exit_stack.aclose()
print("✅ Resources released")
async def main():
"""
Main function that initializes and runs the FastMCP client.
"""
# Verify command line arguments
if len(sys.argv) != 2:
print("❌ Usage: python client.py &lt;http_server_url&gt;")
print("📝 Example: python client.py http://localhost:8000")
print("📝 Note: Now connects to HTTP server instead of executing script")
sys.exit(1)
server_url = sys.argv[1]
# Validate URL format
if not server_url.startswith(('http://', 'https://')):
print("❌ Error: Server URL must start with http:// or https://")
print("📝 Example: python client.py http://localhost:8000")
sys.exit(1)
# Create and run client
client = FastMCPClient()
try:
# Connect to the server
await client.connect_to_server(server_url)
# List available tools after connection
await client.list_available_tools()
# Start chat loop
await client.chat_loop()
except Exception as e:
print(f"❌ Fatal error: {str(e)}")
finally:
# Ensure resources are cleaned up
await client.cleanup()
if __name__ == "__main__":
# Entry point of the script
asyncio.run(main())
Copied
>_ Output
			
Overwriting client_MCP/client.py

Prueba del MCP por httplink image 4

Para probar, primero tenemos que ejecutar el cliente para que se levante la URL y el puerto

	
< > Input
Python
!cd gitHub_MCP_server && source .venv/bin/activate && uv run github_server.py
Copied
>_ Output
			
/Users/macm1/Documents/web/portafolio/posts/gitHub_MCP_server/github_server.py:240: DeprecationWarning: Mount prefixes are now optional and the first positional argument should be the server you want to mount.
mcp.mount("sub_mcp", sub_mcp)
DEBUG: Starting FastMCP GitHub server...
DEBUG: Server name: GitHubMCP
[06/28/25 10:33:36] INFO Starting MCP server 'GitHubMCP' with ]8;id=281189;file:///Users/macm1/Documents/web/portafolio/posts/gitHub_MCP_server/.venv/lib/python3.11/site-packages/fastmcp/server/server.py\server.py]8;;\:]8;id=128713;file:///Users/macm1/Documents/web/portafolio/posts/gitHub_MCP_server/.venv/lib/python3.11/site-packages/fastmcp/server/server.py#1297\1297]8;;\
transport 'streamable-http' on
http://0.0.0.0:8000/mcp/
INFO: Started server process [89401]
INFO: Waiting for application startup.
INFO: Application startup complete.
INFO: Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)

Ahora ejecutamos el cliente, dándole la URL del servidor MCP.

	
< > Input
Python
!cd client_MCP && source .venv/bin/activate && uv run client.py http://localhost:8000/mcp
Copied
>_ Output
			
🔗 Connecting to FastMCP HTTP server: http://localhost:8000/mcp
✅ Client created successfully
🛠️ Available tools (2):
==================================================
📋 sub_mcp_hello_world
Description: Returns a simple greeting.
Parameters:
📋 list_repository_issues
Description: Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
Parameters: owner, repo_name
🤖 FastMCP HTTP client started. Write 'quit', 'q', 'exit', 'salir' to exit.
💬 You can ask questions about GitHub repositories!
📚 The client can use tools from the FastMCP HTTP server
🌐 Connected via Server-Sent Events (SSE)
------------------------------------------------------------
👤 You:

Vemos que se ha establecido la conexión sin problema.

Vuelta del servidor a STDIOlink image 5

Volvemos a establecer STDIO como capa de transporte del servidor

	
< > Input
Python
%%writefile gitHub_MCP_server/github_server.py
import httpx
from typing import Optional
from fastmcp import FastMCP
from github import GITHUB_TOKEN, create_github_headers
# Create FastMCP server
mcp = FastMCP(
name="GitHubMCP",
instructions="This server provides tools, resources and prompts to interact with the GitHub API.",
include_tags={"public"},
exclude_tags={"first_issue"}
)
sub_mcp = FastMCP(
name="SubMCP",
)
@mcp.tool(tags={"public", "production"})
async def list_repository_issues(owner: str, repo_name: str) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 10 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=10"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"private", "development"})
async def list_more_repository_issues(owner: str, repo_name: str) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 100 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=100"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"public", "first_issue"})
async def first_repository_issue(owner: str, repo_name: str) -&gt; list[dict]:
"""
Gets the first issue ever created in a GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list containing information about the first issue created
"""
# Get the first issue by sorting by creation date in ascending order
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=all&amp;sort=created&amp;direction=asc&amp;per_page=1"
print(f"Fetching first issue from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No issues found for this repository.")
return [{"message": "No issues found for this repository."}]
first_issue = issues_data[0]
# Create a detailed summary of the first issue
summary = f"#{first_issue.get('number', 'N/A')}: {first_issue.get('title', 'No title')}"
if first_issue.get('comments', 0) &gt; 0:
summary += f" ({first_issue.get('comments')} comments)"
issue_info = {
"number": first_issue.get("number"),
"title": first_issue.get("title"),
"user": first_issue.get("user", {}).get("login"),
"url": first_issue.get("html_url"),
"state": first_issue.get("state"),
"comments": first_issue.get("comments"),
"created_at": first_issue.get("created_at"),
"updated_at": first_issue.get("updated_at"),
"body": first_issue.get("body", "")[:500] + "..." if len(first_issue.get("body", "")) &gt; 500 else first_issue.get("body", ""),
"summary": summary
}
print(f"Found first issue: #{first_issue.get('number')} created on {first_issue.get('created_at')}")
# Add context information
result = {
"repository": f"{owner}/{repo_name}",
"note": "This is the very first issue created in this repository",
"first_issue": issue_info
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@sub_mcp.tool(tags={"public"})
def hello_world() -&gt; str:
"""
Returns a simple greeting.
"""
return "Hello, world!"
mcp.mount("sub_mcp", sub_mcp)
if __name__ == "__main__":
print("DEBUG: Starting FastMCP GitHub server...")
print(f"DEBUG: Server name: {mcp.name}")
# Initialize and run the server
mcp.run(
transport="stdio"
)
Copied
>_ Output
			
Overwriting gitHub_MCP_server/github_server.py

Argumentos excluídoslink image 6

Servidor MCPlink image 7

Supongamos que queremos tener trazabilidad de la ID del usuario que ha hecho una petición, tendríamos que añadir un parámetro a la tool que se ejecute con dicha información. Pero esa información es irrelevante para el LLM, incluso por temas de seguridad, a lo mejor no queremos que dicha ID se pueda filtrar

Por lo que para que no se le pase un parámetro al LLM, a la hora de definir una tool podemos indicar que se excluya un parámetro mediante exclude_args.

	
< > Input
Python
%%writefile gitHub_MCP_server/github_server.py
import httpx
from fastmcp import FastMCP
from github import GITHUB_TOKEN, create_github_headers
USER_ID = 1234567890
# Create FastMCP server
mcp = FastMCP(
name="GitHubMCP",
instructions="This server provides tools, resources and prompts to interact with the GitHub API.",
include_tags={"public"},
exclude_tags={"first_issue"}
)
sub_mcp = FastMCP(
name="SubMCP",
)
@mcp.tool(
tags={"public", "production"},
exclude_args=["user_id"], # user_id has to be injected by server, not provided by LLM
)
async def list_repository_issues(owner: str, repo_name: str, user_id: int = USER_ID) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 10 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=10"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary,
"requested_by_user_id": user_id
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"private", "development"})
async def list_more_repository_issues(owner: str, repo_name: str) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 100 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=100"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"public", "first_issue"})
async def first_repository_issue(owner: str, repo_name: str) -&gt; list[dict]:
"""
Gets the first issue ever created in a GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list containing information about the first issue created
"""
# Get the first issue by sorting by creation date in ascending order
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=all&amp;sort=created&amp;direction=asc&amp;per_page=1"
print(f"Fetching first issue from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No issues found for this repository.")
return [{"message": "No issues found for this repository."}]
first_issue = issues_data[0]
# Create a detailed summary of the first issue
summary = f"#{first_issue.get('number', 'N/A')}: {first_issue.get('title', 'No title')}"
if first_issue.get('comments', 0) &gt; 0:
summary += f" ({first_issue.get('comments')} comments)"
issue_info = {
"number": first_issue.get("number"),
"title": first_issue.get("title"),
"user": first_issue.get("user", {}).get("login"),
"url": first_issue.get("html_url"),
"state": first_issue.get("state"),
"comments": first_issue.get("comments"),
"created_at": first_issue.get("created_at"),
"updated_at": first_issue.get("updated_at"),
"body": first_issue.get("body", "")[:500] + "..." if len(first_issue.get("body", "")) &gt; 500 else first_issue.get("body", ""),
"summary": summary
}
print(f"Found first issue: #{first_issue.get('number')} created on {first_issue.get('created_at')}")
# Add context information
result = {
"repository": f"{owner}/{repo_name}",
"note": "This is the very first issue created in this repository",
"first_issue": issue_info
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@sub_mcp.tool(tags={"public"})
def hello_world() -&gt; str:
"""
Returns a simple greeting.
"""
return "Hello, world!"
mcp.mount("sub_mcp", sub_mcp)
if __name__ == "__main__":
print("DEBUG: Starting FastMCP GitHub server...")
print(f"DEBUG: Server name: {mcp.name}")
# Initialize and run the server
mcp.run(
transport="stdio"
)
Copied
>_ Output
			
Overwriting gitHub_MCP_server/github_server.py

Como se puede ver, en la tool list_repository_issues hemos indicado que se excluya el parámetro user_id.

@mcp.tool(
tags={"public", "production"},
exclude_args=["user_id"], # user_id has to be injected by server, not provided by LLM
)
async def list_repository_issues(owner: str, repo_name: str, user_id: int = USER_ID) -> list[dict]:

Aunque luego devolvemos "requested_by_user_id": user_id

result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary,
"requested_by_user_id": user_id
}

Es decir, le estamos pasando la ID al LLM en el resultado. Pero en este caso, es para que a la hora de ejecutar la tool veamos que se ha ejecutado con dicha ID.

Contextolink image 8

Podemos pasar información de contexto del servidor al cliente y viceversa.

Servidor MCPlink image 9

Vamos a añadir contexto a nuestro servidor MCP.

	
< > Input
Python
%%writefile gitHub_MCP_server/github_server.py
import httpx
from fastmcp import FastMCP, Context
from github import GITHUB_TOKEN, create_github_headers
USER_ID = 1234567890
# Create FastMCP server
mcp = FastMCP(
name="GitHubMCP",
instructions="This server provides tools, resources and prompts to interact with the GitHub API.",
include_tags={"public"},
exclude_tags={"first_issue"}
)
sub_mcp = FastMCP(
name="SubMCP",
)
@mcp.tool(
tags={"public", "production"},
exclude_args=["user_id"], # user_id has to be injected by server, not provided by LLM
)
async def list_repository_issues(owner: str, repo_name: str, ctx: Context, user_id: int = USER_ID) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
ctx: The context of the request
user_id: The user ID (automatically injected by the server)
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 10 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=10"
ctx.info(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
ctx.info("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
ctx.info(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary,
"requested_by_user_id": user_id
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
ctx.error(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
ctx.error(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"private", "development"})
async def list_more_repository_issues(owner: str, repo_name: str) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 100 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=100"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"public", "first_issue"})
async def first_repository_issue(owner: str, repo_name: str) -&gt; list[dict]:
"""
Gets the first issue ever created in a GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list containing information about the first issue created
"""
# Get the first issue by sorting by creation date in ascending order
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=all&amp;sort=created&amp;direction=asc&amp;per_page=1"
print(f"Fetching first issue from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No issues found for this repository.")
return [{"message": "No issues found for this repository."}]
first_issue = issues_data[0]
# Create a detailed summary of the first issue
summary = f"#{first_issue.get('number', 'N/A')}: {first_issue.get('title', 'No title')}"
if first_issue.get('comments', 0) &gt; 0:
summary += f" ({first_issue.get('comments')} comments)"
issue_info = {
"number": first_issue.get("number"),
"title": first_issue.get("title"),
"user": first_issue.get("user", {}).get("login"),
"url": first_issue.get("html_url"),
"state": first_issue.get("state"),
"comments": first_issue.get("comments"),
"created_at": first_issue.get("created_at"),
"updated_at": first_issue.get("updated_at"),
"body": first_issue.get("body", "")[:500] + "..." if len(first_issue.get("body", "")) &gt; 500 else first_issue.get("body", ""),
"summary": summary
}
print(f"Found first issue: #{first_issue.get('number')} created on {first_issue.get('created_at')}")
# Add context information
result = {
"repository": f"{owner}/{repo_name}",
"note": "This is the very first issue created in this repository",
"first_issue": issue_info
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@sub_mcp.tool(tags={"public"})
def hello_world() -&gt; str:
"""
Returns a simple greeting.
"""
return "Hello, world!"
mcp.mount("sub_mcp", sub_mcp)
if __name__ == "__main__":
print("DEBUG: Starting FastMCP GitHub server...")
print(f"DEBUG: Server name: {mcp.name}")
# Initialize and run the server
mcp.run(
transport="stdio"
)
Copied
>_ Output
			
Overwriting gitHub_MCP_server/github_server.py

Hemos sustituído todos los prints por ctx.info. De esta manera, todas esas líneas de información ahora se pueden imprimir en el cliente si queremos.

Más adelante lo vamos a usar

Crear un resourcelink image 10

Vamos a crear un resource estático en nuestro MCP

Servidor MCPlink image 11

Podemos convertir una función en nuestro servidor en un resource mediante el decorador @mcp.resource(<ENDPOINT>).

Un resource es un endpoint que nos da información. Mientras que una tool puede realizar cambios y/o acciones, un resource solo nos da información.

Vamos a verlo con un ejemplo.

	
< > Input
Python
%%writefile gitHub_MCP_server/github_server.py
import httpx
from fastmcp import FastMCP, Context
from github import GITHUB_TOKEN, create_github_headers
USER_ID = 1234567890
# Create FastMCP server
mcp = FastMCP(
name="GitHubMCP",
instructions="This server provides tools, resources and prompts to interact with the GitHub API.",
include_tags={"public"},
exclude_tags={"first_issue"}
)
sub_mcp = FastMCP(
name="SubMCP",
)
@mcp.tool(
tags={"public", "production"},
exclude_args=["user_id"], # user_id has to be injected by server, not provided by LLM
)
async def list_repository_issues(owner: str, repo_name: str, ctx: Context, user_id: int = USER_ID) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
ctx: The context of the request
user_id: The user ID (automatically injected by the server)
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 10 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=10"
ctx.info(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
ctx.info("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
ctx.info(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary,
"requested_by_user_id": user_id
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
ctx.error(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
ctx.error(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"private", "development"})
async def list_more_repository_issues(owner: str, repo_name: str) -&gt; list[dict]:
"""
Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
"""
# Limit to first 100 issues to avoid very long responses
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=open&amp;per_page=100"
print(f"Fetching issues from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No open issues found for this repository.")
return [{"message": "No open issues found for this repository."}]
issues_summary = []
for issue in issues_data:
# Create a more concise summary
summary = f"#{issue.get('number', 'N/A')}: {issue.get('title', 'No title')}"
if issue.get('comments', 0) &gt; 0:
summary += f" ({issue.get('comments')} comments)"
issues_summary.append({
"number": issue.get("number"),
"title": issue.get("title"),
"user": issue.get("user", {}).get("login"),
"url": issue.get("html_url"),
"comments": issue.get("comments"),
"summary": summary
})
print(f"Found {len(issues_summary)} open issues.")
# Add context information
result = {
"total_found": len(issues_summary),
"repository": f"{owner}/{repo_name}",
"note": "Showing first 10 open issues" if len(issues_summary) == 10 else f"Showing all {len(issues_summary)} open issues",
"issues": issues_summary
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.tool(tags={"public", "first_issue"})
async def first_repository_issue(owner: str, repo_name: str) -&gt; list[dict]:
"""
Gets the first issue ever created in a GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
Returns:
list[dict]: A list containing information about the first issue created
"""
# Get the first issue by sorting by creation date in ascending order
api_url = f"https://api.github.com/repos/{owner}/{repo_name}/issues?state=all&amp;sort=created&amp;direction=asc&amp;per_page=1"
print(f"Fetching first issue from {api_url}...")
async with httpx.AsyncClient() as client:
try:
response = await client.get(api_url, headers=create_github_headers())
response.raise_for_status()
issues_data = response.json()
if not issues_data:
print("No issues found for this repository.")
return [{"message": "No issues found for this repository."}]
first_issue = issues_data[0]
# Create a detailed summary of the first issue
summary = f"#{first_issue.get('number', 'N/A')}: {first_issue.get('title', 'No title')}"
if first_issue.get('comments', 0) &gt; 0:
summary += f" ({first_issue.get('comments')} comments)"
issue_info = {
"number": first_issue.get("number"),
"title": first_issue.get("title"),
"user": first_issue.get("user", {}).get("login"),
"url": first_issue.get("html_url"),
"state": first_issue.get("state"),
"comments": first_issue.get("comments"),
"created_at": first_issue.get("created_at"),
"updated_at": first_issue.get("updated_at"),
"body": first_issue.get("body", "")[:500] + "..." if len(first_issue.get("body", "")) &gt; 500 else first_issue.get("body", ""),
"summary": summary
}
print(f"Found first issue: #{first_issue.get('number')} created on {first_issue.get('created_at')}")
# Add context information
result = {
"repository": f"{owner}/{repo_name}",
"note": "This is the very first issue created in this repository",
"first_issue": issue_info
}
return [result]
except httpx.HTTPStatusError as e:
error_message = e.response.json().get("message", "No additional message from API.")
if e.response.status_code == 403 and GITHUB_TOKEN:
error_message += " (Rate limit with token or token lacks permissions?)"
elif e.response.status_code == 403 and not GITHUB_TOKEN:
error_message += " (Rate limit without token. Consider creating a .env file with GITHUB_TOKEN.)"
print(f"GitHub API error: {e.response.status_code}. {error_message}")
return [{
"error": f"GitHub API error: {e.response.status_code}",
"message": error_message
}]
except Exception as e:
print(f"An unexpected error occurred: {str(e)}")
return [{"error": f"An unexpected error occurred: {str(e)}"}]
@mcp.resource("resource://server_info", tags={"public"})
def server_info() -&gt; str:
"""
Returns information about the server.
"""
return "This is the MCP GitHub server development for MaximoFN blog post"
@sub_mcp.tool(tags={"public"})
def hello_world() -&gt; str:
"""
Returns a simple greeting.
"""
return "Hello, world!"
mcp.mount("sub_mcp", sub_mcp)
if __name__ == "__main__":
print("DEBUG: Starting FastMCP GitHub server...")
print(f"DEBUG: Server name: {mcp.name}")
# Initialize and run the server
mcp.run(
transport="stdio"
)
Copied
>_ Output
			
Overwriting gitHub_MCP_server/github_server.py

Como vemos, hemos creado el resource server_info que nos devuelve una cadena de texto con la información del servidor

Es importante ver que hemos declarado el endpoint resource://server_info, que es obligatorio cada vez que creamos resources

Además, le hemos puesto la tag public, ya que nuestro servidor MCP solo incluye las tools o resources que tengan la tag public.

mcp = FastMCP(
name="GitHubMCP",
instructions="This server provides tools, resources and prompts to interact with the GitHub API.",
include_tags={"public"},
exclude_tags={"first_issue"}
)

Cliente MCPlink image 12

Ahora tenemos que hacer que nuestro cliente pueda ver los resources de nuestro servidor MCP.

	
< > Input
Python
%%writefile client_MCP/client.py
import sys
import asyncio
from contextlib import AsyncExitStack
from anthropic import Anthropic
from dotenv import load_dotenv
from fastmcp import Client
# Load environment variables from .env file
load_dotenv()
class FastMCPClient:
"""
FastMCP client that integrates with Claude to process user queries
and use tools and resources exposed by a FastMCP server.
"""
def __init__(self):
"""Initialize the FastMCP client with Anthropic and resource management."""
self.exit_stack = AsyncExitStack()
self.anthropic = Anthropic()
self.client = None
async def connect_to_server(self, server_script_path: str):
"""
Connect to the specified FastMCP server.
Args:
server_script_path: Path to the server script (Python)
"""
print(f"🔗 Connecting to FastMCP server: {server_script_path}")
# Determine the server type based on the extension
if not server_script_path.endswith('.py'):
raise ValueError(f"Unsupported server type. Use .py files. Received: {server_script_path}")
# Create FastMCP client
self.client = Client(server_script_path)
# Note: FastMCP Client automatically infers transport from .py files
print("✅ Client created successfully")
async def list_available_tools(self):
"""List available tools in the FastMCP server."""
try:
# Get list of tools from the server using FastMCP context
async with self.client as client:
tools = await client.list_tools()
if tools:
print(f" 🛠️ Available tools ({len(tools)}):")
print("=" * 50)
for tool in tools:
print(f"📋 {tool.name}")
if tool.description:
print(f" Description: {tool.description}")
# Show parameters if available
if hasattr(tool, 'inputSchema') and tool.inputSchema:
if 'properties' in tool.inputSchema:
params = list(tool.inputSchema['properties'].keys())
print(f" Parameters: {', '.join(params)}")
print()
else:
print("⚠️ No tools found in the server")
except Exception as e:
print(f"❌ Error listing tools: {str(e)}")
async def list_available_resources(self):
"""List available resources in the FastMCP server."""
try:
# Get list of resources from the server using FastMCP context
async with self.client as client:
resources = await client.list_resources()
if resources:
print(f" 📚 Available resources ({len(resources)}):")
print("=" * 50)
for resource in resources:
print(f"📄 {resource.uri}")
if resource.name:
print(f" Name: {resource.name}")
if resource.description:
print(f" Description: {resource.description}")
if resource.mimeType:
print(f" MIME Type: {resource.mimeType}")
print()
else:
print("⚠️ No resources found in the server")
except Exception as e:
print(f"❌ Error listing resources: {str(e)}")
async def read_resource(self, resource_uri: str):
"""
Read a specific resource from the server.
Args:
resource_uri: URI of the resource to read
Returns:
str: Resource content
"""
try:
async with self.client as client:
result = await client.read_resource(resource_uri)
return result
except Exception as e:
print(f"❌ Error reading resource {resource_uri}: {str(e)}")
return None
async def process_query(self, query: str) -&gt; str:
"""
Process a user query, interacting with Claude and FastMCP tools and resources.
Args:
query: User query
Returns:
str: Final processed response
"""
try:
# Use FastMCP context for all operations
async with self.client as client:
# Get available tools and resources
tools_list = await client.list_tools()
resources_list = await client.list_resources()
# Prepare tools for Claude in correct format
claude_tools = []
for tool in tools_list:
claude_tool = {
"name": tool.name,
"description": tool.description or f"Tool {tool.name}",
"input_schema": tool.inputSchema or {"type": "object", "properties": {}}
}
claude_tools.append(claude_tool)
# Add a special tool for reading resources
if resources_list:
# Convert URIs to strings to avoid AnyUrl object issues
resource_uris = [str(r.uri) for r in resources_list]
claude_tools.append({
"name": "read_mcp_resource",
"description": "Read a resource from the MCP server. Available resources: " +
", ".join(resource_uris),
"input_schema": {
"type": "object",
"properties": {
"resource_uri": {
"type": "string",
"description": "URI of the resource to read"
}
},
"required": ["resource_uri"]
}
})
# Create initial message for Claude
messages = [
{
"role": "user",
"content": query
}
]
# First call to Claude
response = self.anthropic.messages.create(
model="claude-3-5-sonnet-20241022",
max_tokens=6000,
messages=messages,
tools=claude_tools if claude_tools else None
)
# Process Claude's response
response_text = ""
for content_block in response.content:
if content_block.type == "text":
response_text += content_block.text
elif content_block.type == "tool_use":
# Claude wants to use a tool
tool_name = content_block.name
tool_args = content_block.input
tool_call_id = content_block.id
print(f"🔧 Claude wants to use: {tool_name}")
print(f"📝 Arguments: {tool_args}")
try:
if tool_name == "read_mcp_resource":
# Handle resource reading
resource_uri = tool_args.get("resource_uri")
if resource_uri:
tool_result = await client.read_resource(resource_uri)
print(f"📖 Resource read successfully: {resource_uri}")
# Better handling of resource result
if hasattr(tool_result, 'content'):
# If it's a resource response object, extract content
if hasattr(tool_result.content, 'text'):
result_content = tool_result.content.text
else:
result_content = str(tool_result.content)
else:
# If it's already a string or simple object
result_content = str(tool_result)
else:
tool_result = "Error: No resource URI provided"
result_content = tool_result
else:
# Execute regular tool on the FastMCP server
tool_result = await client.call_tool(tool_name, tool_args)
print(f"✅ Tool executed successfully")
result_content = str(tool_result)
# Add tool result to the conversation
messages.append({
"role": "assistant",
"content": response.content
})
# Format result for Claude
if tool_result:
messages.append({
"role": "user",
"content": [{
"type": "tool_result",
"tool_use_id": tool_call_id,
"content": f"Tool result: {result_content}"
}]
})
else:
messages.append({
"role": "user",
"content": [{
"type": "tool_result",
"tool_use_id": tool_call_id,
"content": "Tool executed without response content"
}]
})
# Second call to Claude with the tool result
final_response = self.anthropic.messages.create(
model="claude-3-5-sonnet-20241022",
max_tokens=6000,
messages=messages,
tools=claude_tools if claude_tools else None
)
# Extract text from the final response
for final_content in final_response.content:
if final_content.type == "text":
response_text += final_content.text
except Exception as e:
error_msg = f"❌ Error executing {tool_name}: {str(e)}"
print(error_msg)
response_text += f" {error_msg}"
return response_text
except Exception as e:
error_msg = f"❌ Error processing query: {str(e)}"
print(error_msg)
return error_msg
async def chat_loop(self):
"""
Main chat loop with user interaction.
"""
print(" 🤖 FastMCP client started. Write 'quit', 'q', 'exit', 'salir' to exit.")
print("💬 You can ask questions about GitHub repositories!")
print("📚 The client can use tools and resources from the FastMCP server")
print("-" * 60)
while True:
try:
# Request user input
user_input = input(" 👤 You: ").strip()
if user_input.lower() in ['quit', 'q', 'exit', 'salir']:
print("👋 Bye!")
break
if not user_input:
continue
print(" 🤔 Claude is thinking...")
# Process query
response = await self.process_query(user_input)
# Show response
print(f" 🤖 Claude: {response}")
except KeyboardInterrupt:
print(" 👋 Disconnecting...")
break
except Exception as e:
print(f" ❌ Error in chat: {str(e)}")
continue
async def cleanup(self):
"""Clean up resources and close connections."""
print("🧹 Cleaning up resources...")
# FastMCP Client cleanup is handled automatically by context manager
await self.exit_stack.aclose()
print("✅ Resources released")
async def main():
"""
Main function that initializes and runs the FastMCP client.
"""
# Verify command line arguments
if len(sys.argv) != 2:
print("❌ Usage: python client.py &lt;path_to_fastmcp_server&gt;")
print("📝 Example: python client.py ../MCP_github/github_server.py")
sys.exit(1)
server_script_path = sys.argv[1]
# Create and run client
client = FastMCPClient()
try:
# Connect to the server
await client.connect_to_server(server_script_path)
# List available tools and resources after connection
await client.list_available_tools()
await client.list_available_resources()
# Start chat loop
await client.chat_loop()
except Exception as e:
print(f"❌ Fatal error: {str(e)}")
finally:
# Ensure resources are cleaned up
await client.cleanup()
if __name__ == "__main__":
# Entry point of the script
asyncio.run(main())
Copied
>_ Output
			
Overwriting client_MCP/client.py

Hemos creado los métodos list_available_resources y read_resource para poder leer los recursos que tenemos en el servidor MCP.

Prueba del resourcelink image 13

Ejecutamos el cliente para poder probar el resource que hemos creado

	
< > Input
Python
!cd client_MCP && source .venv/bin/activate && python client.py ../gitHub_MCP_server/github_server.py
Copied
>_ Output
			
🔗 Connecting to FastMCP server: ../gitHub_MCP_server/github_server.py
✅ Client created successfully
/Users/macm1/Documents/web/portafolio/posts/gitHub_MCP_server/github_server.py:255: DeprecationWarning: Mount prefixes are now optional and the first positional argument should be the server you want to mount.
mcp.mount("sub_mcp", sub_mcp)
[06/28/25 11:09:01] INFO Starting MCP server 'GitHubMCP' with transport 'stdio' server.py:1246
🛠️ Available tools (2):
==================================================
📋 sub_mcp_hello_world
Description: Returns a simple greeting.
Parameters:
📋 list_repository_issues
Description: Lists open issues for a given GitHub repository.
Args:
owner: The owner of the repository (e.g., 'modelcontextprotocol')
repo_name: The name of the repository (e.g., 'python-sdk')
ctx: The context of the request
user_id: The user ID (automatically injected by the server)
Returns:
list[dict]: A list of dictionaries, each containing information about an issue
Parameters: owner, repo_name
📚 Available resources (1):
==================================================
📄 resource://server_info
Name: server_info
Description: Returns information about the server.
MIME Type: text/plain
🤖 FastMCP client started. Write 'quit', 'q', 'exit', 'salir' to exit.
💬 You can ask questions about GitHub repositories!
📚 The client can use tools and resources from the FastMCP server
------------------------------------------------------------
👤 You: Tell me the server info
🤔 Claude is thinking...
🔧 Claude wants to use: read_mcp_resource
📝 Arguments: {'resource_uri': 'resource://server_info'}
📖 Resource read successfully: resource://server_info
🤖 Claude: I'll help you read the server information using the `read_mcp_resource` function with the specific resource URI for server info.The server information indicates that this is the MCP GitHub server development environment for MaximoFN blog post.
👤 You: q
👋 Bye!
🧹 Cleaning up resources...
✅ Resources released

Vemos que nos da una lista de resources

📚 Available resources (1):
==================================================
📄 resource://server_info
Name: server_info
Description: Returns information about the server.
MIME Type: text/plain

Y que cuando le pedimos la información del servidor usa el resource server_info que acabamos de crear.

👤 You: Tell me the server info

🤔 Claude is thinking...
🔧 Claude wants to use: read_mcp_resource
📝 Arguments: {'resource_uri': 'resource://server_info'}
📖 Resource read successfully: resource://server_info

🤖 Claude: I'll help you read the server information using the `read_mcp_resource` function with the specific resource URI for server info. The server information indicates that this is the MCP GitHub server development environment for MaximoFN blog post.

---

➡️ **Continúa en la Parte 3: resources avanzados y prompts**.

Seguir leyendo

Últimos posts -->

¿Has visto estos proyectos?

Gymnasia

Gymnasia Gymnasia
React Native
Expo
TypeScript
FastAPI
Next.js
OpenAI
Anthropic

Aplicación móvil de entrenamiento personal con asistente de IA, biblioteca de ejercicios, seguimiento de rutinas, dieta y medidas corporales

Horeca chatbot

Horeca chatbot Horeca chatbot
Python
LangChain
PostgreSQL
PGVector
React
Kubernetes
Docker
GitHub Actions

Chatbot conversacional para cocineros de hoteles y restaurantes. Un cocinero, jefe de cocina o camaeror de un hotel o restaurante puede hablar con el chatbot para obtener información de recetas y menús. Pero además implementa agentes, con los cuales puede editar o crear nuevas recetas o menús

Naviground

Naviground Naviground
Ver todos los proyectos -->
>_ Disponible para proyectos

¿Tienes un proyecto con IA?

Hablemos.

maximofn@gmail.com

Especialista en Machine Learning e Inteligencia Artificial. Desarrollo soluciones con IA generativa, agentes inteligentes y modelos personalizados.

¿Quieres ver alguna charla?

Últimas charlas -->

¿Quieres mejorar con estos tips?

Últimos tips -->

Usa esto en local

Los espacios de Hugging Face nos permite ejecutar modelos con demos muy sencillas, pero ¿qué pasa si la demo se rompe? O si el usuario la elimina? Por ello he creado contenedores docker con algunos espacios interesantes, para poder usarlos de manera local, pase lo que pase. De hecho, es posible que si pinchas en alún botón de ver proyecto te lleve a un espacio que no funciona.

Flow edit

Flow edit Flow edit

Edita imágenes con este modelo de Flow. Basándose en SD3 o FLUX puedes editar cualquier imagen y generar nuevas

FLUX.1-RealismLora

FLUX.1-RealismLora FLUX.1-RealismLora
Ver todos los contenedores -->
>_ Disponible para proyectos

¿Tienes un proyecto con IA?

Hablemos.

maximofn@gmail.com

Especialista en Machine Learning e Inteligencia Artificial. Desarrollo soluciones con IA generativa, agentes inteligentes y modelos personalizados.

¿Quieres entrenar tu modelo con estos datasets?

short-jokes-dataset

HuggingFace

Dataset de chistes en inglés

Uso: Fine-tuning de modelos de generación de texto humorístico

231K filas 2 columnas 45 MB
Ver en HuggingFace →

opus100

HuggingFace

Dataset con traducciones de inglés a español

Uso: Entrenamiento de modelos de traducción inglés-español

1M filas 2 columnas 210 MB
Ver en HuggingFace →

netflix_titles

HuggingFace

Dataset con películas y series de Netflix

Uso: Análisis de catálogo de Netflix y sistemas de recomendación

8.8K filas 12 columnas 3.5 MB
Ver en HuggingFace →
Ver más datasets -->