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
- Clone or download this repository
- 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 numberb(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
-
Open Cursor Settings:
- Press
Cmd+,(Mac) orCtrl+,(Windows/Linux) - Or go to
Cursor > Preferences > Settings
- Press
-
Navigate to MCP Settings:
- Search for "MCP" in the settings search bar
- Click on "Model Context Protocol" settings
-
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
-
Open Cursor Settings JSON:
- Press
Cmd+Shift+P(Mac) orCtrl+Shift+P(Windows/Linux) - Type "Preferences: Open Settings (JSON)"
- Select it
- Press
-
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.
-
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:
- Opening a chat with the AI assistant
- Asking it to add numbers: "Can you add 15 and 27 for me?"
- The AI will use your MCP server to perform the calculation
Troubleshooting
- Server not found: Make sure the path to
mcp.jsis correct and the file exists - Permission errors: Ensure you have execute permissions on the Node.js binary
- Dependencies missing: Run
npm installin the project directory first - Port conflicts: This server uses stdio, so no port conflicts should occur
Development
Project Structure
mcp.js- Main server implementationpackage.json- Node.js project configurationREADME.md- This file
Dependencies
@modelcontextprotocol/sdk- Official MCP SDKzod- Type validation library
License
ISC