MCPサーバー作成の公式クイックスタートをやってみた

> curl -LsSf https://astral.sh/uv/install.sh | sh
downloading uv 0.6.12 aarch64-apple-darwin
no checksums to verify
installing to /Users/username/.local/bin
  uv
  uvx
everything's installed!

bash-5.2$ uv init weather
bash-5.2$ cd weather/
bash-5.2$ uv venv
bash-5.2$ source .venv/bin/activate
(weather) bash-5.2$

(weather) bash-5.2$ uv add "mcp[cli]" httpx
Resolved 28 packages in 1.05s
Prepared 26 packages in 261ms
Installed 26 packages in 61ms
 + annotated-types==0.7.0
 + anyio==4.9.0
 + certifi==2025.1.31
 + click==8.1.8
 + h11==0.14.0
 + httpcore==1.0.7
 + httpx==0.28.1
 + httpx-sse==0.4.0
 + idna==3.10
 + markdown-it-py==3.0.0
 + mcp==1.6.0
 + mdurl==0.1.2
 + pydantic==2.11.2
 + pydantic-core==2.33.1
 + pydantic-settings==2.8.1
 + pygments==2.19.1
 + python-dotenv==1.1.0
 + rich==14.0.0
 + shellingham==1.5.4
 + sniffio==1.3.1
 + sse-starlette==2.2.1
 + starlette==0.46.1
 + typer==0.15.2
 + typing-extensions==4.13.1
 + typing-inspection==0.4.0
 + uvicorn==0.34.0

from typing import Any
import httpx
from mcp.server.fastmcp import FastMCP

# Initialize FastMCP server
mcp = FastMCP("weather")

# Constants
NWS_API_BASE = "https://api.weather.gov"
USER_AGENT = "weather-app/1.0"

async def make_nws_request(url: str) -> dict[str, Any] | None:
    """Make a request to the NWS API with proper error handling."""
    headers = {
        "User-Agent": USER_AGENT,
        "Accept": "application/geo+json"
    }
    async with httpx.AsyncClient() as client:
        try:
            response = await client.get(url, headers=headers, timeout=30.0)
            response.raise_for_status()
            return response.json()
        except Exception:
            return None

def format_alert(feature: dict) -> str:
    """Format an alert feature into a readable string."""
    props = feature["properties"]
    return f"""
Event: {props.get('event', 'Unknown')}
Area: {props.get('areaDesc', 'Unknown')}
Severity: {props.get('severity', 'Unknown')}
Description: {props.get('description', 'No description available')}
Instructions: {props.get('instruction', 'No specific instructions provided')}
"""

@mcp.tool()
async def get_alerts(state: str) -> str:
    """Get weather alerts for a US state.

    Args:
        state: Two-letter US state code (e.g. CA, NY)
    """
    url = f"{NWS_API_BASE}/alerts/active/area/{state}"
    data = await make_nws_request(url)

    if not data or "features" not in data:
        return "Unable to fetch alerts or no alerts found."

    if not data["features"]:
        return "No active alerts for this state."

    alerts = [format_alert(feature) for feature in data["features"]]
    return "\n---\n".join(alerts)

@mcp.tool()
async def get_forecast(latitude: float, longitude: float) -> str:
    """Get weather forecast for a location.

    Args:
        latitude: Latitude of the location
        longitude: Longitude of the location
    """
    # First get the forecast grid endpoint
    points_url = f"{NWS_API_BASE}/points/{latitude},{longitude}"
    points_data = await make_nws_request(points_url)

    if not points_data:
        return "Unable to fetch forecast data for this location."

    # Get the forecast URL from the points response
    forecast_url = points_data["properties"]["forecast"]
    forecast_data = await make_nws_request(forecast_url)

    if not forecast_data:
        return "Unable to fetch detailed forecast."

    # Format the periods into a readable forecast
    periods = forecast_data["properties"]["periods"]
    forecasts = []
    for period in periods[:5]:  # Only show next 5 periods
        forecast = f"""
{period['name']}:
Temperature: {period['temperature']}°{period['temperatureUnit']}
Wind: {period['windSpeed']} {period['windDirection']}
Forecast: {period['detailedForecast']}
"""
        forecasts.append(forecast)

    return "\n---\n".join(forecasts)
if __name__ == "__main__":
    # Initialize and run the server
    mcp.run(transport='stdio')

# Initialize FastMCP server
mcp = FastMCP("weather")

# Constants
NWS_API_BASE = "https://api.weather.gov"
USER_AGENT = "weather-app/1.0"

(weather) bash-5.2$ uv run weather.py

{
    "mcpServers": {
        "weather": {
            "command": "/Users/***/.local/bin/uv",
            "args": [
                "--directory",
                "＜weather.pyが存在するディレクトリを絶対パスで指定＞",
                "run",
                "weather.py"
            ]
        }
    }
}