ggmcp: Cursor rule for Windsurf

Cursor Rules for MCP Tool Generation

Tool Definition Guidelines

1. Use the @mcp.tool() decorator

   • All tools must be defined using the @mcp.tool() decorator
   • This properly registers the function as an MCP tool
   • Include proper type hints for parameters and return values

2. Methods must be async

   • All tool methods should be defined as async functions
   • Use async def for all tool definitions
   • Use appropriate async libraries and patterns (e.g., httpx.AsyncClient instead of requests)

3. Include descriptive docstrings

   • Each tool must have a clear, descriptive docstring
   • Docstrings should explain what the tool does and describe parameters

Examples of correct tool implementations:

@mcp.tool()
async def calculate_bmi(weight_kg: float, height_m: float) -> float:
    """Calculate BMI given weight in kg and height in meters"""
    return weight_kg / (height_m**2)


@mcp.tool()
async def fetch_weather(city: str) -> str:
    """Fetch current weather for a city"""
    async with httpx.AsyncClient() as client:
        response = await client.get(f"https://api.weather.com/{city}")
        return response.text

Common Mistakes to Avoid

1. Don't use synchronous functions

   • Incorrect: def my_tool():
   • Correct: async def my_tool():

2. Don't forget the decorator

   • Incorrect: async def my_tool():
   • Correct: @mcp.tool()\nasync def my_tool():

3. Don't use blocking HTTP libraries

   • Incorrect: requests.get(...)
   • Correct: async with httpx.AsyncClient() as client: await client.get(...)

---

title: "Don't use uvicorn or fastapi with MCP" description: "MCP has native server capabilities, external web servers are not needed" severity: warning

Don't use uvicorn or fastapi with MCP/FastMCP

Rule Details

MCP and FastMCP have their own server implementations that can run directly without external web servers like uvicorn or fastapi.

❌ Incorrect

# Incorrect: Using uvicorn with MCP
import uvicorn
from mcp.server.fastmcp import FastMCP

mcp = FastMCP("MyServer")

if __name__ == "__main__":
    uvicorn.run(mcp.app, host="0.0.0.0", port=8000)  # Wrong