MCP Weather Server

Instructions

Implementation Reference

• main.ts:20-49 (handler)

  The handler function that performs geocoding to find coordinates for the city and then fetches current weather data from Open-Meteo API, returning the JSON data as text content.

  async ({ city }) => {
      const response = await fetch(`https://geocoding-api.open-meteo.com/v1/search?name=${city}&count=10&language=en&format=json`)
      const data = await response.json();
  
      if (data.length === 0) {
          return {
              content: [
                  {
                      type: "text",
                      text: `No se encontró información del clima para la ciudad: ${city}.`
                  },
              ],
          };
      }
  
      const { latitude, longitude } = data.results[0]
  
      const weatherResponse = await fetch(`https://api.open-meteo.com/v1/forecast?latitude=${latitude}&longitude=${longitude}&hourly=temperature_2m¤t=temperature_2m,is_day,precipitation,rain&forecast_days=1`)
  
      const weatherData = await weatherResponse.json();
  
      return {
          content: [
              {
                  type: "text",
                  text: JSON.stringify(weatherData, null, 2),
              },
          ],
      };
  }

• main.ts:17-19 (schema)

  Input schema using Zod: requires a 'city' string parameter.

  {
      city: z.string().describe('Nombre de la ciudad'),
  },

• main.ts:14-50 (registration)

  The server.tool call that registers the 'fetch-weather' tool with name, description, input schema, and handler function.

  server.tool(
      'fetch-weather',
      'Tool to fetch the weather of a city',
      {
          city: z.string().describe('Nombre de la ciudad'),
      },
      async ({ city }) => {
          const response = await fetch(`https://geocoding-api.open-meteo.com/v1/search?name=${city}&count=10&language=en&format=json`)
          const data = await response.json();
  
          if (data.length === 0) {
              return {
                  content: [
                      {
                          type: "text",
                          text: `No se encontró información del clima para la ciudad: ${city}.`
                      },
                  ],
              };
          }
  
          const { latitude, longitude } = data.results[0]
  
          const weatherResponse = await fetch(`https://api.open-meteo.com/v1/forecast?latitude=${latitude}&longitude=${longitude}&hourly=temperature_2m¤t=temperature_2m,is_day,precipitation,rain&forecast_days=1`)
  
          const weatherData = await weatherResponse.json();
  
          return {
              content: [
                  {
                      type: "text",
                      text: JSON.stringify(weatherData, null, 2),
                  },
              ],
          };
      }
  );