MCP Server with OpenAI Integration

Instructions

Implementation Reference

• src/index.ts:17-26 (handler)

  The core handler function that implements the logic for the 'get_weather' tool, generating simulated weather information for the given city and unit.

  async function getWeatherInfo(city: string, unit: "celsius" | "fahrenheit" = "celsius"): Promise<string> {
    // Simulate weather API call
    const temperature = Math.floor(Math.random() * 30) + 10; // Random temp between 10-40
    const conditions = ["sunny", "cloudy", "rainy", "partly cloudy"];
    const condition = conditions[Math.floor(Math.random() * conditions.length)];
    
    const tempDisplay = unit === "fahrenheit" ? `${Math.round(temperature * 9/5 + 32)}°F` : `${temperature}°C`;
    
    return `Weather in ${city}: ${tempDisplay}, ${condition}`;
  }

• src/index.ts:11-14 (schema)

  Zod schema used for input validation of the 'get_weather' tool parameters.

  const WeatherToolSchema = z.object({
    city: z.string().describe("The city to get weather information for"),
    unit: z.enum(["celsius", "fahrenheit"]).optional().default("celsius").describe("Temperature unit"),
  });

• src/index.ts:66-70 (registration)

  Registration of the 'get_weather' tool in the MCP server's tool listing handler.

  this.server.setRequestHandler(ListToolsRequestSchema, async () => {
    return {
      tools: [weatherTool],
    };
  });

• src/index.ts:73-92 (handler)

  MCP server request handler for tool calls, dispatching to getWeatherInfo when 'get_weather' is called and returning the result.

  this.server.setRequestHandler(CallToolRequestSchema, async (request) => {
    const { name, arguments: args } = request.params;
  
    switch (name) {
      case "get_weather":
        const { city, unit } = WeatherToolSchema.parse(args);
        const weatherInfo = await getWeatherInfo(city, unit);
        return {
          content: [
            {
              type: "text",
              text: weatherInfo,
            },
          ],
        };
  
      default:
        throw new Error(`Unknown tool: ${name}`);
    }
  });

• src/index.ts:29-48 (schema)

  Definition of the 'get_weather' tool including its MCP input schema for tool discovery.

  const weatherTool: Tool = {
    name: "get_weather",
    description: "Get current weather information for a specific city",
    inputSchema: {
      type: "object",
      properties: {
        city: {
          type: "string",
          description: "The city to get weather information for"
        },
        unit: {
          type: "string",
          enum: ["celsius", "fahrenheit"],
          default: "celsius",
          description: "Temperature unit"
        }
      },
      required: ["city"]
    },
  };