Weather MCP Server

Instructions

Implementation Reference

• weather_api.py:43-98 (handler)

  Core implementation of the get_current_weather tool. Fetches current weather from OpenWeatherMap API with caching, mock data fallback, and comprehensive data formatting.

  async def get_current_weather(self, location: str) -> Dict:
      """
      Get current weather for a location.
      
      Args:
          location: City name or location string
          
      Returns:
          Dictionary with weather data
      """
      location = self._normalize_location(location)
      
      # Check cache first
      cached = self._get_from_cache(f"current_{location}")
      if cached:
          return cached
      
      # If no API key, return mock data
      if not self.api_key:
          return self._get_mock_current_weather(location)
      
      try:
          async with httpx.AsyncClient() as client:
              url = f"{self.base_url}/weather"
              params = {
                  "q": location,
                  "appid": self.api_key,
                  "units": "metric"
              }
              response = await client.get(url, params=params, timeout=10.0)
              response.raise_for_status()
              data = response.json()
              
              # Format the response
              result = {
                  "location": data.get("name", location),
                  "country": data.get("sys", {}).get("country", ""),
                  "temperature": data.get("main", {}).get("temp", 0),
                  "feels_like": data.get("main", {}).get("feels_like", 0),
                  "humidity": data.get("main", {}).get("humidity", 0),
                  "pressure": data.get("main", {}).get("pressure", 0),
                  "description": data.get("weather", [{}])[0].get("description", ""),
                  "wind_speed": data.get("wind", {}).get("speed", 0),
                  "wind_direction": data.get("wind", {}).get("deg", 0),
                  "visibility": data.get("visibility", 0) / 1000 if data.get("visibility") else None,
                  "clouds": data.get("clouds", {}).get("all", 0),
                  "timestamp": datetime.now().isoformat()
              }
              
              self._cache_data(f"current_{location}", result)
              return result
              
      except httpx.HTTPError as e:
          # Fallback to mock data on API error
          return self._get_mock_current_weather(location)

• main.py:30-43 (registration)

  Registers the get_current_weather tool with the MCP server, including name, description, and input schema.

  Tool(
      name="get_current_weather",
      description="Get current weather conditions for a specific location",
      inputSchema={
          "type": "object",
          "properties": {
              "location": {
                  "type": "string",
                  "description": "City name or location (e.g., 'New York', 'London')"
              }
          },
          "required": ["location"]
      }
  ),

• main.py:33-42 (schema)

  Defines the input schema for the get_current_weather tool, specifying the required 'location' parameter.

  inputSchema={
      "type": "object",
      "properties": {
          "location": {
              "type": "string",
              "description": "City name or location (e.g., 'New York', 'London')"
          }
      },
      "required": ["location"]
  }

• main.py:85-97 (handler)

  MCP server handler dispatch for get_current_weather tool call, validates input and delegates to WeatherAPI instance.

  if name == "get_current_weather":
      location = arguments.get("location", "")
      if not location:
          return [TextContent(
              type="text",
              text="Error: location parameter is required"
          )]
      
      weather_data = await weather_api.get_current_weather(location)
      return [TextContent(
          type="text",
          text=json.dumps(weather_data, indent=2)
      )]

• weather_api.py:209-226 (helper)

  Helper function providing mock weather data when API key is missing or on API errors.

  def _get_mock_current_weather(self, location: str) -> Dict:
      """Return mock current weather data for demo purposes."""
      import random
      return {
          "location": location,
          "country": "US",
          "temperature": round(random.uniform(15, 30), 1),
          "feels_like": round(random.uniform(14, 29), 1),
          "humidity": random.randint(40, 80),
          "pressure": random.randint(1000, 1020),
          "description": random.choice(["clear sky", "few clouds", "scattered clouds", "broken clouds", "shower rain", "rain", "thunderstorm", "snow", "mist"]),
          "wind_speed": round(random.uniform(0, 15), 1),
          "wind_direction": random.randint(0, 360),
          "visibility": round(random.uniform(5, 10), 1),
          "clouds": random.randint(0, 100),
          "timestamp": datetime.now().isoformat(),
          "note": "Mock data - set WEATHER_API_KEY in .env for real data"
      }