FastMCP Demo

Instructions

Implementation Reference

• src/basic-mcp/server.ts:86-96 (handler)

  The specific handler logic for the 'hello' tool within the CallToolRequestSchema request handler. It greets the user by name or defaults to 'World'.

  if (name === "hello") {
    const userName = (args?.name as string) || "World";
    return {
      content: [
        {
          type: "text",
          text: `Hello, ${userName}! Welcome to MCP!`,
        },
      ],
    };
  }

• src/basic-mcp/server.ts:41-55 (schema)

  The tool metadata and input schema definition for 'hello' returned in ListTools response.

  {
    name: "hello",
    description: "A simple greeting tool that says hello",
    inputSchema: {
      type: "object",
      properties: {
        name: {
          type: "string",
          description: "The name to greet",
        },
      },
      required: ["name"],
    },
  },
  {

• src/basic-mcp/server.ts:38-82 (registration)

  The registration of the ListToolsRequestSchema handler, which advertises the available tools including 'hello'.

  server.setRequestHandler(ListToolsRequestSchema, async () => {
    return {
      tools: [
        {
          name: "hello",
          description: "A simple greeting tool that says hello",
          inputSchema: {
            type: "object",
            properties: {
              name: {
                type: "string",
                description: "The name to greet",
              },
            },
            required: ["name"],
          },
        },
        {
          name: "calculate",
          description: "Perform basic arithmetic calculations",
          inputSchema: {
            type: "object",
            properties: {
              operation: {
                type: "string",
                enum: ["add", "subtract", "multiply", "divide"],
                description: "The arithmetic operation to perform",
              },
              a: {
                type: "number",
                description: "First number",
              },
              b: {
                type: "number",
                description: "Second number",
              },
            },
            required: ["operation", "a", "b"],
          },
        },
      ],
    };
  });
  
  // Handle tool execution

• src/fastmcp-example/server.ts:25-27 (handler)

  The execute handler for the 'hello' tool in the FastMCP example, returning a simple greeting string.

  execute: async (args) => {
    return `Hello, ${args.name}! Welcome to MCP!`;
  },

• src/fastmcp-example/server.ts:19-28 (registration)

  The complete registration of the 'hello' tool using FastMCP's addTool API, including schema (via Zod), description, and inline handler.

  server.addTool({
    name: "hello",
    description: "A simple greeting tool that says hello",
    parameters: z.object({
      name: z.string().describe("The name to greet"),
    }),
    execute: async (args) => {
      return `Hello, ${args.name}! Welcome to MCP!`;
    },
  });