MongoDB MCP Server

import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; import { CallToolRequestSchema, ListToolsRequestSchema, ListPromptsRequestSchema, GetPromptRequestSchema } from "@modelcontextprotocol/sdk/types.js"; import mongoose from 'mongoose'; import dotenv from 'dotenv'; // Load environment variables dotenv.config(); // MongoDB connection URI const MONGODB_URI = process.env.MONGODB_URI || 'mongodb://localhost:27017/mcp-mongo'; // Global variables to track server state let server = null; let transport = null; let isShuttingDown = false; // Define the User schema const userSchema = new mongoose.Schema({ name: { type: String, required: true }, email: { type: String, required: true, unique: true }, age: { type: Number, required: true }, createdAt: { type: Date, default: Date.now } }); const User = mongoose.model('User', userSchema); // Connect to MongoDB with proper error handling async function connectDB() { try { await mongoose.connect(MONGODB_URI, { serverSelectionTimeoutMS: 5000, // Timeout after 5s instead of 30s heartbeatFrequencyMS: 2000, // Check connection every 2s }); console.error('✅ Connected to MongoDB'); } catch (error) { console.error('❌ MongoDB connection error:', error); process.exit(1); } } // Graceful shutdown function async function gracefulShutdown(signal) { if (isShuttingDown) { console.error('⚠️ Already shutting down, forcing exit...'); process.exit(1); } isShuttingDown = true; console.error(`🛑 Received ${signal}, shutting down gracefully...`); try { // Close MCP server connection if (transport) { console.error('🔌 Closing MCP transport...'); await transport.close(); } // Close MongoDB connection if (mongoose.connection.readyState === 1) { console.error('🗄️ Closing MongoDB connection...'); await mongoose.connection.close(); console.error('✅ MongoDB connection closed'); } console.error('✅ Graceful shutdown completed'); process.exit(0); } catch (error) { console.error('❌ Error during shutdown:', error); process.exit(1); } } // Set up signal handlers for graceful shutdown process.on('SIGINT', () => gracefulShutdown('SIGINT')); process.on('SIGTERM', () => gracefulShutdown('SIGTERM')); process.on('SIGHUP', () => gracefulShutdown('SIGHUP')); // Handle uncaught exceptions and rejections process.on('uncaughtException', (error) => { console.error('❌ Uncaught Exception:', error); gracefulShutdown('uncaughtException'); }); process.on('unhandledRejection', (reason, promise) => { console.error('❌ Unhandled Rejection at:', promise, 'reason:', reason); gracefulShutdown('unhandledRejection'); }); // Start MCP Server async function main() { try { await connectDB(); server = new Server( { name: "mcp-mongo", version: "1.0.0", }, { capabilities: { tools: { listChanged: true }, prompts: { listChanged: true }, }, } ); // Handle tool listing server.setRequestHandler(ListToolsRequestSchema, async () => { return { tools: [ { name: "create-user", description: "Create a new user in the database", inputSchema: { type: "object", properties: { name: { type: "string", description: "User's full name" }, email: { type: "string", description: "User's email address" }, age: { type: "number", description: "User's age" } }, required: ["name", "email", "age"] } }, { name: "get-user", description: "Retrieve a user by email address", inputSchema: { type: "object", properties: { email: { type: "string", description: "User's email address" } }, required: ["email"] } }, { name: "list-users", description: "List all users in the database", inputSchema: { type: "object", properties: { limit: { type: "number", description: "Maximum number of users to return (default: 10)" } } } } ] }; }); // Handle tool calls server.setRequestHandler(CallToolRequestSchema, async (request) => { // Check if we're shutting down if (isShuttingDown) { return { content: [ { type: "text", text: "❌ Server is shutting down, cannot process request" } ], isError: true }; } const { name, arguments: args } = request.params; try { switch (name) { case "create-user": { const { name: userName, email, age } = args; const user = new User({ name: userName, email, age }); await user.save(); return { content: [ { type: "text", text: `✅ User created successfully!\n\n${JSON.stringify(user.toObject(), null, 2)}` } ] }; } case "get-user": { const { email } = args; const user = await User.findOne({ email }); if (!user) { return { content: [ { type: "text", text: `❌ User with email "${email}" not found.` } ] }; } return { content: [ { type: "text", text: `👤 User found:\n\n${JSON.stringify(user.toObject(), null, 2)}` } ] }; } case "list-users": { const { limit = 10 } = args; const users = await User.find().limit(limit).sort({ createdAt: -1 }); return { content: [ { type: "text", text: `📋 Found ${users.length} users:\n\n${JSON.stringify(users.map(u => u.toObject()), null, 2)}` } ] }; } default: throw new Error(`Unknown tool: ${name}`); } } catch (error) { return { content: [ { type: "text", text: `❌ Error: ${error instanceof Error ? error.message : String(error)}` } ], isError: true }; } }); // Handle prompt listing server.setRequestHandler(ListPromptsRequestSchema, async () => { return { prompts: [ { name: "create-new-user", description: "Interactive prompt to create a new user" }, { name: "find-user-by-email", description: "Interactive prompt to find a user by email" } ] }; }); // Handle prompt requests server.setRequestHandler(GetPromptRequestSchema, async (request) => { const { name } = request.params; switch (name) { case "create-new-user": return { description: "Create a new user in the database", messages: [ { role: "user", content: { type: "text", text: `Let's create a new user! Please provide the following details: 1. **Full Name** (required) 2. **Email Address** (required, must be unique) 3. **Age** (required, must be a number) I'll help you add this user to the MongoDB database.` } } ] }; case "find-user-by-email": return { description: "Look up a user by email address", messages: [ { role: "user", content: { type: "text", text: "Please provide the email address of the user you'd like to find in the database." } } ] }; default: throw new Error(`Unknown prompt: ${name}`); } }); // Connect to stdin/stdout transport transport = new StdioServerTransport(); await server.connect(transport); console.error("🚀 MCP MongoDB Server is running and ready to accept connections!"); // Keep the process alive process.stdin.resume(); } catch (error) { console.error("❌ Fatal error starting server:", error); await gracefulShutdown('startup-error'); } } // Start the server main().catch(async (error) => { console.error("❌ Fatal error in main:", error); await gracefulShutdown('main-error'); });