Python SDK

# With uv (recommended)
uv add "mcp[cli]"

# With pip
pip install "mcp[cli]"

# server.py
from mcp.server.fastmcp import FastMCP

mcp = FastMCP("My Server")

@mcp.tool()
def add(a: int, b: int) -> int:
    """Add two numbers together."""
    return a + b

@mcp.resource("data://greeting/{name}")
def greeting(name: str) -> str:
    return f"Hello, {name}!"

if __name__ == "__main__":
    mcp.run()

mcp dev server.py

# Basic install
uv run mcp install server.py

# Install with environment variables
uv run mcp install server.py -v API_KEY=your_key -f .env

from mcp.server.fastmcp import FastMCP
from mcp.server.auth.provider import TokenVerifier, AccessToken
from mcp.server.auth.settings import AuthSettings
from pydantic import AnyHttpUrl

class MyTokenVerifier(TokenVerifier):
    async def verify_token(self, token: str) -> AccessToken | None:
        # Validate token against your auth server
        if token == "valid-token":
            return AccessToken(token=token, scopes=["read"])
        return None

mcp = FastMCP(
    "Protected Server",
    token_verifier=MyTokenVerifier(),
    auth=AuthSettings(
        issuer_url=AnyHttpUrl("https://auth.example.com"),
        resource_server_url=AnyHttpUrl("http://localhost:3001"),
        required_scopes=["read"],
    ),
)