MCP サーバーエコシステム — 国土交通省地理空間 MCP の事例から見る展開

# npm でインストール
npx -y @mlit/geospatial-mcp-server

# または globaにインストール
npm install -g @mlit/geospatial-mcp-server

// .mcp.json
{
  "mcpServers": {
    "mlit-geospatial": {
      "command": "npx",
      "args": ["-y", "@mlit/geospatial-mcp-server"],
      "env": {
        "MLIT_API_KEY": "your-api-key"
      }
    }
  }
}

// server.ts
import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';

const server = new Server({
  name: 'my-mcp-server',
  version: '1.0.0',
}, {
  capabilities: {
    prompts: {},
    resources: {},
    tools: {},
  },
});

// ツール定義
server.setRequestHandler('tools/call', async (request) => {
  const { name, arguments: args } = request.params;
  
  if (name === 'my_tool') {
    return {
      content: [{ type: 'text', text: '結果' }],
    };
  }
  
  throw new Error(`Unknown tool: ${name}`);
});

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

// 読み取り専用データソース
server.setRequestHandler('resources/read', async (request) => {
  const { uri } = request.params;
  
  if (uri.startsWith('stats://')) {
    const data = await fetchStatistics(uri);
    return {
      contents: [{
        uri,
        mimeType: 'application/json',
        text: JSON.stringify(data),
      }],
    };
  }
});

// プロンプトテンプレート
server.setRequestHandler('prompts/get', async (request) => {
  const { name, arguments: args } = request.params;
  
  if (name === 'analyze_data') {
    return {
      messages: [{
        role: 'user',
        content: {
          type: 'text',
          text: `以下のデータを分析してください:\n\n${args.data}`,
        },
      }],
    };
  }
});

// 実行ツール
server.setRequestHandler('tools/call', async (request) => {
  const { name, arguments: args } = request.params;
  
  if (name === 'send_email') {
    await sendEmail(args.to, args.subject, args.body);
    return {
      content: [{ type: 'text', text: 'メールを送信しました' }],
    };
  }
});

// API キー認証
const apiKey = process.env.API_KEY;

server.setRequestHandler('tools/call', async (request) => {
  if (!apiKey) {
    throw new Error('API key required');
  }
  
  // ツール実行
});

// 簡易レートリミット
const rateLimiter = new Map<string, number[]>();

function checkRateLimit(clientId: string, limit: number, window: number): boolean {
  const now = Date.now();
  const calls = rateLimiter.get(clientId) || [];
  const recentCalls = calls.filter(t => now - t < window);
  
  if (recentCalls.length >= limit) {
    return false;
  }
  
  recentCalls.push(now);
  rateLimiter.set(clientId, recentCalls);
  return true;
}

// 入力バリデーション
function validateGeocodeRequest(input: unknown): { address: string } {
  if (typeof input !== 'object' || input === null) {
    throw new Error('Invalid input');
  }
  
  const { address } = input as Record<string, unknown>;
  if (typeof address !== 'string' || address.length === 0) {
    throw new Error('Address is required');
  }
  
  return { address };
}