Weather MCP Server

Instructions

Implementation Reference

• main.ts:19-51 (handler)

  The handler function for the 'get-weather' tool. It invokes queryOllama to fetch weather data for the given city, handles errors gracefully, and returns the response in MCP content format.

  async ({ city }) => {
      console.log(`🌤️ MCP tool called for: ${city}`);
      const toolStartTime = Date.now();
      
      try {
          const response = await queryOllama(city);
          const toolEndTime = Date.now();
          
          console.log(`✅ MCP tool completed in ${toolEndTime - toolStartTime}ms`);
          
          return {
              content: [
                  {
                      type: "text",
                      text: response,
                  }
              ]
          };
      } catch (error) {
          const toolEndTime = Date.now();
          console.error(`❌ MCP tool failed after ${toolEndTime - toolStartTime}ms:`, error);
          
          // Return a helpful error message instead of throwing
          return {
              content: [
                  {
                      type: "text",
                      text: `Unable to get weather for ${city}. Ollama may be slow or unavailable. Error: ${error instanceof Error ? error.message : 'Unknown error'}`,
                  }
              ]
          };
      }
  }

• main.ts:16-18 (schema)

  Zod schema defining the input parameter 'city' for the get-weather tool.

  {
      city: z.string().describe("The city to get the weather for"),
  },

• main.ts:13-52 (registration)

  Registration of the 'get-weather' tool using McpServer.tool(), including name, description, input schema, and handler reference.

  server.tool(
      "get-weather",
      "Tool to get the weather for a given city",
      {
          city: z.string().describe("The city to get the weather for"),
      },
      async ({ city }) => {
          console.log(`🌤️ MCP tool called for: ${city}`);
          const toolStartTime = Date.now();
          
          try {
              const response = await queryOllama(city);
              const toolEndTime = Date.now();
              
              console.log(`✅ MCP tool completed in ${toolEndTime - toolStartTime}ms`);
              
              return {
                  content: [
                      {
                          type: "text",
                          text: response,
                      }
                  ]
              };
          } catch (error) {
              const toolEndTime = Date.now();
              console.error(`❌ MCP tool failed after ${toolEndTime - toolStartTime}ms:`, error);
              
              // Return a helpful error message instead of throwing
              return {
                  content: [
                      {
                          type: "text",
                          text: `Unable to get weather for ${city}. Ollama may be slow or unavailable. Error: ${error instanceof Error ? error.message : 'Unknown error'}`,
                      }
                  ]
              };
          }
      }
  );

• ollamaClient.ts:26-47 (helper)

  Core helper function that queries Ollama for weather information using HTTP API with fallback to CLI, implementing the actual LLM-based weather query logic.

  export async function queryOllama(city: string): Promise<string> {
    console.log(`🌤️ Querying weather for ${city}...`);
    const startTime = Date.now();
    
    try {
      const result = await queryOllamaHTTP(city);
      const endTime = Date.now();
      console.log(`✅ Query completed in ${endTime - startTime}ms`);
      return result;
    } catch (error) {
      console.error("❌ HTTP API failed, trying CLI...");
      try {
        const result = await queryOllamaCLI(city);
        const endTime = Date.now();
        console.log(`✅ CLI query completed in ${endTime - startTime}ms`);
        return result;
      } catch (cliError) {
        console.error("❌ Both HTTP and CLI failed");
        throw error;
      }
    }
  }