Weather MCP Server

Instructions

Implementation Reference

• server.py:185-193 (handler)

  Handler logic for the weather_forecast tool within the tools/call method. Validates location 'q' and days (1-14), then fetches forecast data using the shared fetch function.

  elif tool_name == "weather_forecast":
      q = arguments.get("q")
      days = arguments.get("days", 1)
      if not q:
          raise ValueError("Location (q) is required")
      if days < 1 or days > 14:
          raise ValueError("Days must be between 1 and 14")
      result = await fetch("forecast.json", {"q": q, "days": days})
      content = json.dumps(result, indent=2)

• server.py:128-146 (registration)

  Registration of the weather_forecast tool in the tools/list response, including name, description, and input schema.

  {
      "name": "weather_forecast",
      "description": "Get weather forecast (1-14 days) for a location",
      "inputSchema": {
          "type": "object",
          "properties": {
              "q": {
                  "type": "string",
                  "description": "Location query (city name, lat/lon, postal code, etc)"
              },
              "days": {
                  "type": "integer",
                  "description": "Number of days (1-14)",
                  "default": 1
              }
          },
          "required": ["q"]
      }
  },

• server.py:131-145 (schema)

  Input schema for weather_forecast tool, specifying parameters 'q' (required) and 'days' (optional, default 1).

  "inputSchema": {
      "type": "object",
      "properties": {
          "q": {
              "type": "string",
              "description": "Location query (city name, lat/lon, postal code, etc)"
          },
          "days": {
              "type": "integer",
              "description": "Number of days (1-14)",
              "default": 1
          }
      },
      "required": ["q"]
  }

• server.py:42-80 (helper)

  Shared helper function that performs the actual API call to WeatherAPI.com for all weather tools, including forecast.

  async def fetch(endpoint: str, params: dict) -> dict:
      """Perform async GET to WeatherAPI and return JSON."""
      logger.debug(f"fetch() called with endpoint: {endpoint}, params: {params}")
      
      if not WEATHER_API_KEY:
          logger.error("Weather API key not set.")
          raise Exception("Weather API key not set.")
  
      params["key"] = WEATHER_API_KEY
      url = f"https://api.weatherapi.com/v1/{endpoint}"
      logger.info(f"Requesting {url}")
      
      async with httpx.AsyncClient() as client:
          logger.debug("HTTPx client created")
          try:
              resp = await client.get(url, params=params)
              logger.debug(f"HTTP response received: status={resp.status_code}")
              
              if resp.status_code != 200:
                  try:
                      error_data = resp.json()
                      detail = error_data.get("error", {}).get("message", resp.text)
                  except:
                      detail = resp.text
                  logger.error(f"WeatherAPI error {resp.status_code}: {detail}")
                  raise Exception(f"WeatherAPI error {resp.status_code}: {detail}")
                  
              data = resp.json()
              logger.debug(f"JSON parsing successful")
              logger.info(f"WeatherAPI success: {url}")
              return data
              
          except httpx.RequestError as e:
              logger.error(f"HTTPX request error: {e}")
              raise Exception(f"Request error: {e}")
          except Exception as e:
              logger.error(f"Unexpected error: {e}")
              raise Exception(f"Unexpected error: {e}")