The Minimal Server

Module 4 · Section 4 of 9

The Minimal Server

Create src/index.ts:

import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import {
  CallToolRequestSchema,
  ListToolsRequestSchema,
} from "@modelcontextprotocol/sdk/types.js";

const server = new Server(
  { name: "my-server", version: "1.0.0" },
  { capabilities: { tools: {} } }
);

server.setRequestHandler(ListToolsRequestSchema, async () => ({
  tools: [
    {
      name: "hello",
      description: "Returns a greeting",
      inputSchema: {
        type: "object",
        properties: {
          name: {
            type: "string",
            description: "The name to greet",
          },
        },
        required: ["name"],
      },
    },
  ],
}));

server.setRequestHandler(CallToolRequestSchema, async (request) => {
  if (request.params.name === "hello") {
    const name = request.params.arguments?.name as string;
    return {
      content: [{ type: "text", text: `Hello, ${name}!` }],
    };
  }
  throw new Error(`Unknown tool: ${request.params.name}`);
});

const transport = new StdioServerTransport();
await server.connect(transport);

That’s a complete MCP server. It exposes one tool. Claude can call it. Build it, configure it in settings.json, and it works.