The MCP TypeScript SDK: Building clients and servers

npm install @modelcontextprotocol/sdk zod
npm install --save-dev typescript tsx @types/node

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";

const server = new McpServer({
  name: "calculator-server",
  version: "1.0.0",
});

server.registerTool(
  "add",
  {
    title: "Add numbers",
    description: "Add two numbers and return the total.",
    inputSchema: {
      a: z.number().describe("The first number."),
      b: z.number().describe("The second number."),
    },
  },
  async ({ a, b }) => ({
    content: [
      {
        type: "text",
        text: String(a + b),
      },
    ],
  }),
);

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

src/
  server.ts
  tools/
    orders.ts
    customers.ts
  resources/
    policies.ts
  prompts/
    support.ts
  services/
    api-client.ts

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";

const client = new Client({
  name: "calculator-client",
  version: "1.0.0",
});

const transport = new StdioClientTransport({
  command: "npx",
  args: ["tsx", "src/server.ts"],
});

await client.connect(transport);

const tools = await client.listTools();
console.log(tools.tools.map((tool) => tool.name));

const result = await client.callTool({
  name: "add",
  arguments: { a: 2, b: 3 },
});

console.log(result);
await client.close();

npx @modelcontextprotocol/inspector npx tsx src/server.ts