Weather Server

Instructions

This unique feature allows you to compare weather at two different places side-by-side.

Args:
    location1: First location (city name or "lat,lon" format, e.g., "New York" or "40.7128,-74.0060")
    location2: Second location (city name or "lat,lon" format, e.g., "Los Angeles" or "34.0522,-118.2437")

Implementation Reference

• weather.py:293-388 (handler)

  The main handler function for the 'compare_weather' tool. It parses locations (city names or coordinates), fetches forecast data using NWS API, and returns a formatted side-by-side comparison of temperature, wind, humidity, precip chance, and short forecasts, including temperature difference insight.

  @mcp.tool()
  async def compare_weather(location1: str, location2: str) -> str:
      """Compare current weather conditions between two locations.
      
      This unique feature allows you to compare weather at two different places side-by-side.
  
      Args:
          location1: First location (city name or "lat,lon" format, e.g., "New York" or "40.7128,-74.0060")
          location2: Second location (city name or "lat,lon" format, e.g., "Los Angeles" or "34.0522,-118.2437")
      """
      def parse_location(loc: str) -> tuple[float, float] | None:
          """Parse location string to coordinates.
          
          Only parses if the string is clearly in "lat,lon" format (both parts are numeric).
          Returns None for city names (even if they contain commas like "New York, NY").
          """
          # Check if it's in "lat,lon" format
          if "," in loc:
              parts = loc.split(",")
              # Only try to parse if we have exactly 2 parts
              if len(parts) == 2:
                  try:
                      # Try to parse both parts as floats
                      lat_str = parts[0].strip()
                      lon_str = parts[1].strip()
                      lat, lon = float(lat_str), float(lon_str)
                      # Validate coordinates are in valid ranges
                      if validate_coordinates(lat, lon):
                          return (lat, lon)
                  except ValueError:
                      # If parsing fails, it's not coordinates (probably a city name with comma)
                      pass
          # Not in coordinate format, will need geocoding
          return None
  
      # Get coordinates for both locations
      # Try parsing as coordinates first (e.g., "40.7128,-74.0060")
      coords1 = parse_location(location1)
      if not coords1:
          # If not coordinates, try geocoding the city name
          coords1 = await geocode_location(location1)
          if not coords1:
              return f"Error: Could not find coordinates for '{location1}'. Please check the city name or use 'lat,lon' format (e.g., '40.7128,-74.0060')."
  
      coords2 = parse_location(location2)
      if not coords2:
          # If not coordinates, try geocoding the city name
          coords2 = await geocode_location(location2)
          if not coords2:
              return f"Error: Could not find coordinates for '{location2}'. Please check the city name or use 'lat,lon' format (e.g., '40.7128,-74.0060')."
  
      # Get forecast data for both locations
      forecast1 = await get_forecast_data(coords1[0], coords1[1])
      forecast2 = await get_forecast_data(coords2[0], coords2[1])
  
      if not forecast1:
          return f"Unable to fetch weather data for '{location1}' (coordinates: {coords1[0]}, {coords1[1]}). The location may be outside NWS coverage area (US territories only)."
      if not forecast2:
          return f"Unable to fetch weather data for '{location2}' (coordinates: {coords2[0]}, {coords2[1]}). The location may be outside NWS coverage area (US territories only)."
  
      loc1_info = forecast1.get("_location", {})
      loc2_info = forecast2.get("_location", {})
      loc1_str = f"{loc1_info.get('city', location1)}, {loc1_info.get('state', 'Unknown')}"
      loc2_str = f"{loc2_info.get('city', location2)}, {loc2_info.get('state', 'Unknown')}"
  
      # Get current period (first period) for each location
      period1 = forecast1["properties"]["periods"][0] if forecast1["properties"]["periods"] else None
      period2 = forecast2["properties"]["periods"][0] if forecast2["properties"]["periods"] else None
  
      if not period1 or not period2:
          return "Unable to get current conditions for comparison."
  
      result = f"🌤️  Weather Comparison\n"
      result += f"{'='*60}\n\n"
      result += f"{loc1_str:<30} | {loc2_str}\n"
      result += f"{'-'*60}\n"
      result += f"Temperature: {period1['temperature']}°{period1['temperatureUnit']:<25} | {period2['temperature']}°{period2['temperatureUnit']}\n"
      result += f"Wind: {period1['windSpeed']} {period1['windDirection']:<25} | {period2['windSpeed']} {period2['windDirection']}\n"
      
      if period1.get('relativeHumidity') and period2.get('relativeHumidity'):
          result += f"Humidity: {period1['relativeHumidity']['value']}%{'':<25} | {period2['relativeHumidity']['value']}%\n"
      
      if period1.get('probabilityOfPrecipitation') and period2.get('probabilityOfPrecipitation'):
          result += f"Precip Chance: {period1['probabilityOfPrecipitation']['value']}%{'':<22} | {period2['probabilityOfPrecipitation']['value']}%\n"
      
      result += f"\nForecast:\n"
      result += f"{loc1_str}: {period1['detailedForecast']}\n"
      result += f"{loc2_str}: {period2['detailedForecast']}\n"
  
      # Add temperature difference analysis
      temp_diff = period1['temperature'] - period2['temperature']
      if abs(temp_diff) > 5:
          warmer = loc1_str if temp_diff > 0 else loc2_str
          result += f"\n💡 {warmer} is {abs(temp_diff)}°{period1['temperatureUnit']} warmer!"
  
      return result

• weather.py:293-293 (registration)

  The @mcp.tool() decorator registers the compare_weather function as an MCP tool.

  @mcp.tool()

• weather.py:299-302 (schema)

  Input schema defined in the function signature and docstring: two string parameters for locations, returns a string comparison.

  Args:
      location1: First location (city name or "lat,lon" format, e.g., "New York" or "40.7128,-74.0060")
      location2: Second location (city name or "lat,lon" format, e.g., "Los Angeles" or "34.0522,-118.2437")
  """