My MCP Server

A simple Model Context Protocol (MCP) server that provides an addition tool for adding two numbers together.

Overview

This MCP server implements a basic arithmetic tool that can add two numbers. It's built using the official MCP SDK and demonstrates how to create a custom MCP server.

Features

• Addition Tool: Adds two numbers together

• MCP Protocol: Follows the Model Context Protocol specification

• Type Safety: Uses Zod for input validation

Installation

1. Clone or download this repository

2. Install dependencies:

   npm install

Usage

Running the Server

To run the MCP server:

node mcp.js

The server will start and listen for MCP protocol messages via stdio.

Available Tools

Addition Tool

• Name: add

• Description: Add two numbers together

• Parameters:

  • a (number): First number

  • b (number): Second number

• Returns: The sum of the two numbers as text

Example Usage

When connected to an MCP client, you can use the addition tool like this:

{
  "tool": "add",
  "parameters": {
    "a": 5,
    "b": 3
  }
}

This would return: 8

Adding to Cursor

To use this MCP server in Cursor, you need to configure it in your Cursor settings:

Method 1: Using Cursor Settings UI

1. Open Cursor Settings:

   • Press Cmd+, (Mac) or Ctrl+, (Windows/Linux)

   • Or go to Cursor > Preferences > Settings

2. Navigate to MCP Settings:

   • Search for "MCP" in the settings search bar

   • Click on "Model Context Protocol" settings

3. Add the Server:

   • Click "Add Server" or the "+" button

   • Configure the server with these settings:

     Name: Addition Server
     Command: node
     Args: [path/to/your/mcp.js]
     Cwd: [path/to/your/project/directory]

Method 2: Using Settings JSON

1. Open Cursor Settings JSON:

   • Press Cmd+Shift+P (Mac) or Ctrl+Shift+P (Windows/Linux)

   • Type "Preferences: Open Settings (JSON)"

   • Select it

2. Add MCP Configuration: Add this configuration to your settings JSON:

   {
     "mcp.servers": {
       "addition-server": {
         "command": "node",
         "args": ["/Users/slav/Documents/dev/first-mcp/mcp.js"],
         "cwd": "/Users/slav/Documents/dev/first-mcp"
       }
     }
   }

   Important: Replace the paths with your actual project directory path.

3. Restart Cursor:

   • Close and reopen Cursor for the changes to take effect

Using the Addition Tool in Cursor

Once configured, you can use the addition tool in Cursor by:

1. Opening a chat with the AI assistant

2. Asking it to add numbers: "Can you add 15 and 27 for me?"

3. The AI will use your MCP server to perform the calculation

Troubleshooting

• Server not found: Make sure the path to mcp.js is correct and the file exists

• Permission errors: Ensure you have execute permissions on the Node.js binary

• Dependencies missing: Run npm install in the project directory first

• Port conflicts: This server uses stdio, so no port conflicts should occur

Development

Project Structure

• mcp.js - Main server implementation

• package.json - Node.js project configuration

• README.md - This file

Dependencies

• @modelcontextprotocol/sdk - Official MCP SDK

• zod - Type validation library

License

ISC