Weather MCP Server

Instructions

Args:
    latitude: Latitude of the location
    longitude: Longitude of the location

Implementation Reference

• weather.py:78-112 (handler)

  The handler function for the 'get_forecast' tool. It is registered via the @mcp.tool() decorator. Retrieves the weather forecast for a given latitude and longitude by querying the National Weather Service API, parsing the response, and formatting the next 5 forecast periods into a readable string.

  @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)

• weather.py:16-28 (helper)

  Helper function used by get_forecast to make asynchronous HTTP requests to the NWS API with proper headers, timeout, and error handling.

  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"}
      # Creates an HTTP client using httpx library (async alternative to requests)
      # async with ensures client closes properly
      async with httpx.AsyncClient() as client:
          try:
              response = await client.get(url, headers=headers, timeout=30.0)
              response.raise_for_status()  # Raises error if status code is 4xx/5xx
              return response.json()
          # If anything fails, returns None instead of crashing
          except Exception:
              return None

• weather.py:78-78 (registration)

  The @mcp.tool() decorator registers the get_forecast function as an MCP tool, making it available for invocation by language models.

  @mcp.tool()