作る

ひな形

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: 'my-server', version: '1.0.0' });

server.registerTool(
	'my_tool',
	{
		title: '表示名',
		description: 'いつ使うかを書く。モデルはこれを読んで呼ぶ',
		inputSchema: { arg: z.string().describe('引数の説明') },
	},
	async ({ arg }) => ({ content: [{ type: 'text', text: `受け取った: ${arg}` }] }),
);

await server.connect(new StdioServerTransport());

登録する・確かめる

手で叩く

@(
'{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-11-25","capabilities":{},"clientInfo":{"name":"手","version":"1.0"}}}'
'{"jsonrpc":"2.0","method":"notifications/initialized"}'
'{"jsonrpc":"2.0","id":2,"method":"tools/list"}'
) -join "`n" | node server.mjs

版を確かめる

入力と出力

入力の形（zod）

返し方

伝える

進捗を送る（そのまま使える形）

async ({ seconds }, extra) => {
	const token = extra._meta?.progressToken;

	for (let i = 1; i <= seconds; i++) {
		await sleep(1000);
		if (token === undefined) continue;
		await extra.sendNotification({
			method: 'notifications/progress',
			params: { progressToken: token, progress: i, total: seconds, message: `${i}/${seconds}` },
		});
	}

	return { content: [{ type: 'text', text: '終わった' }] };
}

運ぶ

テストから呼ぶ

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

const transport = new StdioClientTransport({
	command: process.execPath,
	args: ['server.mjs'],
	env: { ...process.env, MEMO_FILE: '...' },
	stderr: 'ignore',
});

const client = new Client({ name: 'tests', version: '1.0.0' }, { capabilities: {} });
await client.connect(transport);

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

await client.close();