MCP Server Setup with JavaScript

This guide walks you through setting up a Model Context Protocol (MCP) server using JavaScript.

Prerequisites

• Node.js (v16 or higher)
• npm or yarn package manager
• latest VS Code

Setup Instructions

1. Initialize Your Project

npm init -y

2. Install Dependencies

npm install @modelcontextprotocol/sdk zod

3. Create Project Structure

mkdir src
# or on Windows: md src

touch src/index.js
# or on Windows: new-item src\index.js

4. Create Your MCP Server

Add the following code to src/index.js:

#!/usr/bin/env node

const { McpServer } = require("@modelcontextprotocol/sdk/server/mcp.js");
const { StdioServerTransport } = require("@modelcontextprotocol/sdk/server/stdio.js");
const { z } = require("zod");

// Create an MCP server
const server = new McpServer({
  name: "demo-server",
  version: "1.0.0"
});

// Add an addition tool
server.registerTool(
  "add",
  {
    title: "Addition Tool",
    description: "Add two numbers",
    inputSchema: { a: z.number(), b: z.number() }
  },
  async ({ a, b }) => ({
    content: [{ type: "text", text: String(a + b) }]
  })
);

// Start receiving messages on stdin and sending messages on stdout
const transport = new StdioServerTransport();
server.connect(transport);

Running Your Server

Run your MCP server with:

node src/index.js

Project Structure

your-project/
├── src/
│   └── index.js          # Main server implementation
├── package.json          # Project configuration
└── README.md            # This file

Next Steps

• Add more tools to your MCP server using server.registerTool()
• Implement resources using server.registerResource()
• Add error handling and logging
• Test your server with an MCP client

Additional Resources

• MCP JavaScript SDK Documentation
• MCP Specification
• Example MCP Servers

Troubleshooting

Common Issues

1. Permission denied on Linux/macOS: Make sure your script file is executable: chmod 755 src/index.js
2. Module resolution errors: Ensure you are using the correct file extensions in your require/import statements
3. Import errors: Use .js extensions in your require/import statements