Weather MCP Server

Instructions

Implementation Reference

• src/weather-service.ts:8-26 (handler)

  Core handler function that implements the get_current_weather tool logic: normalizes the input location, fetches mock weather data if available, or generates random data, and adds a current timestamp.

  async getCurrentWeather(location: string): Promise<WeatherData> {
    // Normalize location name using location mapping
    const normalizedLocation = this.normalizeLocation(location);
    
    if (mockWeatherData[normalizedLocation]) {
      return {
        ...mockWeatherData[normalizedLocation],
        timestamp: new Date().toISOString()
      };
    }
    
    // If location not found, return random weather data
    const randomData = getRandomWeatherData();
    return {
      ...randomData,
      location: location,
      timestamp: new Date().toISOString()
    };
  }

• src/types.ts:1-13 (schema)

  TypeScript interface defining the structure of the WeatherData returned by the get_current_weather tool.

  export interface WeatherData {
    location: string;
    temperature: number;
    humidity: number;
    windSpeed: number;
    windDirection: string;
    condition: string;
    description: string;
    pressure: number;
    visibility: number;
    uvIndex: number;
    timestamp: string;
  }

• src/index.ts:38-51 (registration)

  Tool registration in the stdio MCP server (index.ts): defines name, description, and input schema for list tools response.

  {
    name: 'get_current_weather',
    description: 'Get current weather information for a specified location',
    inputSchema: {
      type: 'object',
      properties: {
        location: {
          type: 'string',
          description: 'Location name (e.g., Hong Kong, Tokyo, London)',
        },
      },
      required: ['location'],
    },
  },

• src/index.ts:117-128 (registration)

  Tool call handler dispatch in stdio MCP server: handles 'get_current_weather' case by calling the weather service and formatting response.

  case 'get_current_weather': {
    const { location } = args as { location: string };
    const weather = await this.weatherService.getCurrentWeather(location);
    return {
      content: [
        {
          type: 'text',
          text: JSON.stringify(weather, null, 2),
        },
      ],
    };
  }

• src/weather-service.ts:110-122 (helper)

  Helper method used by the handler to normalize location strings for lookup in mock data.

  private normalizeLocation(location: string): string {
    const lowerLocation = location.toLowerCase().trim();
    
    // Check if location exists in mapping
    if (locationMapping[lowerLocation]) {
      return locationMapping[lowerLocation];
    }
    
    // Fallback to original normalization
    return lowerLocation
      .replace(/\s+/g, '-')
      .replace(/[^a-z0-9-]/g, '');
  }