MCP Servers

Instructions

Implementation Reference

• src/weather/index.ts:23-40 (registration)

  Registration of the 'get-current-weather' MCP tool using server.tool(), including description, input schema, and handler function.

    "get-current-weather",
    "Get current weather for a location",
    {
      city: z.string().describe("City name (e.g. Beijing, London)"),
      country: z.string().optional().describe("Country code (e.g. CN, GB)")
    },
    async ({ city, country }) => {
      const weatherText = await weatherController.getCurrentWeather(city, country);
      return {
        content: [
          {
            type: "text",
            text: weatherText,
          },
        ],
      };
    }
  );

• src/weather/index.ts:25-28 (schema)

  Zod schema for tool inputs: city (required string), country (optional string).

  {
    city: z.string().describe("City name (e.g. Beijing, London)"),
    country: z.string().optional().describe("Country code (e.g. CN, GB)")
  },

• src/weather/index.ts:29-39 (handler)

  Inline handler function for the tool: extracts parameters, calls WeatherController.getCurrentWeather(), and returns formatted MCP content response.

  async ({ city, country }) => {
    const weatherText = await weatherController.getCurrentWeather(city, country);
    return {
      content: [
        {
          type: "text",
          text: weatherText,
        },
      ],
    };
  }

• src/weather/controllers/weather.ts:10-25 (helper)

  WeatherController.getCurrentWeather(): fetches raw weather data from service and formats it into a human-readable string with temperature, conditions, humidity, etc.

  async getCurrentWeather(city: string, country?: string): Promise<string> {
    const weatherData = await this.weatherService.getCurrentWeather(city, country);
  
    if (!weatherData) {
      return `Failed to retrieve weather data for ${country ? `${city}, ${country}` : city}`;
    }
  
    return [
      `Current weather in ${weatherData.name}, ${weatherData.sys.country}:`,
      `Temperature: ${weatherData.main.temp}°C (Feels like: ${weatherData.main.feels_like}°C)`,
      `Conditions: ${weatherData.weather[0].main} - ${weatherData.weather[0].description}`,
      `Humidity: ${weatherData.main.humidity}%`,
      `Wind Speed: ${weatherData.wind.speed} m/s`,
      `Pressure: ${weatherData.main.pressure} hPa`,
    ].join("\n");
  }

• src/weather/service/weather.ts:35-38 (helper)

  WeatherService.getCurrentWeather(): builds location query and calls makeRequest to fetch current weather data from OpenWeatherMap API.

  async getCurrentWeather(city: string, country?: string): Promise<WeatherData | null> {
    const query = country ? `${city},${country}` : city;
    return this.makeRequest<WeatherData>("weather", { q: query });
  }