Weather MCP Server

Instructions

Implementation Reference

• src/weather/server.py:36-70 (handler)

  The handler function for the 'get_forecast' tool. It is decorated with @mcp.tool() for registration and implements the logic to retrieve and format weather forecast data from the National Weather Service (NWS) API based on latitude and longitude.

      @mcp.tool()
      async def get_forecast(latitude: float, longitude: float) -> str:
          """Get weather forecast for a location.
  
          Args:
              latitude: Latitude of the location (recommended: up to 4 decimal places)
              longitude: Longitude of the location (recommended: up to 4 decimal places)
          """
          # 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)

• src/weather/server.py:75-87 (helper)

  Helper function used by get_forecast to make HTTP requests to the NWS API with proper headers 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",
      }
      async with httpx.AsyncClient(follow_redirects=True) as client:
          try:
              response = await client.get(url, headers=headers, timeout=30.0)
              response.raise_for_status()
              return response.json()
          except Exception:
              return None