MCP (Model Context Protocol)

Creating MCP Servers

A Simple npx-based MCP Server

This project provides a simple MCP server that can be executed via npx. The server includes an "add" tool that performs addition of two numbers.

chmod +x npx-server.js

To inspect the server, run:

npx @modelcontextprotocol/inspector npx -y /path-to/npx-server/your-server-js-file.js

e.g.

npx @modelcontextprotocol/inspector npx -y /Users/flo/Builds/learning/npx-server.js

Usage

Running the Server

You can run this MCP server in several ways:

1. Via npx (recommended):

   npx learning

2. Direct execution:

   ./npx-server.js

3. With Node.js:

   node npx-server.js

Available Tools

• add: Adds two numbers together
  • Parameters: a (number), b (number)
  • Returns: The sum as a text string

Testing with MCP Inspector

The MCP Inspector provides a web interface to test your server:

npx @modelcontextprotocol/inspector npx -y learning

This will:

1. Start the MCP Inspector
2. Launch your server via npx
3. Open a web interface where you can test the "add" tool

MCP Client Configuration

Using with Claude Desktop, Cursor, or Windsurf

To use this server in Claude Desktop, Cursor, or Windsurf, add the following configuration:

{
  "mcpServers": {
    "npx-server": {
      "command": "npx",
      "args": [
        "-y",
        "/Users/flo/Builds/learning/npx-server.js"
      ]
    }
  }
}

Note: Replace /Users/flo/Builds/learning/npx-server.js with the actual path to your npx-server.js file.

Configuration File Locations:

• Claude Desktop (macOS): ~/Library/Application Support/Claude/claude_desktop_config.json
• Claude Desktop (Windows): %APPDATA%\Claude\claude_desktop_config.json
• Cursor: Add to your Cursor MCP settings
• Windsurf: Add to your Windsurf MCP settings

Alternative: Using the published package

If you publish this package to npm, you can use a simpler configuration:

{
  "mcpServers": {
    "npx-server": {
      "command": "npx",
      "args": ["-y", "learning"]
    }
  }
}

Installation

npm install

Dependencies

• @modelcontextprotocol/sdk: MCP SDK for creating servers
• zod: Schema validation for tool parameters

Publish an MCP service to the NPM Registry

You'll also need to update the package name to start with your org, e.g. "@trelis/npx-server"

npm install
npm run build  # Ensures build script exists, even if no compilation is needed. You don't need this if it's a simple javascript MCP.

3. Build and prepare your package:

• For simple JavaScript projects, the build script might just be a placeholder
• Add a minimal build script to package.json if missing:

"scripts": {
  "build": "echo \"No build step required\" && exit 0"
}

4. Publish the package:

npm publish --access public  # Use --access public for open-source packages