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:
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:
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
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
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.js
is correct and the file existsPermission errors: Ensure you have execute permissions on the Node.js binary
Dependencies missing: Run
npm install
in the project directory firstPort 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
This server cannot be installed
remote-capable server
The server can be hosted and run remotely because it primarily relies on remote services or has no dependency on the local environment.
A simple demonstration MCP server that provides a basic arithmetic tool for adding two numbers together, showcasing how to build custom MCP servers with input validation.