Js MCP Server

🚀 JS MCP Server

A JavaScript-based MCP server component that integrates the WebAssembly SDK for easy use and rapid deployment.

🚀 Quick Start

📦 Installation

To start using the JS MCP server, follow these steps:

git clone https://github.com/justin-echternach/js-mcp-server.git
cd js-mcp-server
npm install -g @bytecodealliance/componentize-js @bytecodealliance/jco
npm install

🔨 Build

To build the project and generate the WebAssembly module:

npm run build

This will use Vite to package the JavaScript code and generate the dist/js-mcp-server.wasm file.

✨ Features

⚙️ Customization

You can customize the server by adding or modifying handlers (also known as tools). Handlers are located in the server.js file and stored in the handlers directory. To add a new handler:

1. Create a new JavaScript file in the handlers directory and implement your handling logic.
2. Import your handler in server.js.
3. Add your handler to the tools object in the createMcpServer function call, similar to how EchoTool, KgTool, and FetchDogTool are registered.

For example, to add a new tool named MyTool:

import { myTool } from './handlers/my-tool';

// In server.js
const server = new MCP.Server({
  tools: {
    ...defaultTools,
    myTool: myTool
  }
});

🛠️ Handler Development Guide

Each handler should export the following:

• id: A string, the unique identifier of the tool.
• name: A string, the name of the tool.
• description: A string, the description of the tool.
• method: A function, the handling logic.

Here is an example code:

export const myTool = {
  id: 'my-tool-id',
  name: 'My Tool Name',
  description: 'This is a custom tool that does something.',
  method: async (context, parameters) => {
    // Handling logic
    return { result: 'processed' };
  }
};

📊 Using Postgres and HTTP Interfaces

Postgres Query

The SDK provides functions to query the database, for example:

import { query } from '../sdk/database';

export async function handleDatabaseQuery(context, parameters) {
  try {
    const result = await query('SELECT * FROM my_table WHERE id = $1', [parameters.id]);
    return { data: result };
  } catch (error) {
    return { error: error.message };
  }
}

HTTP Client

The SDK provides convenient HTTP client methods:

import { get, post } from '../sdk/http';

export async function fetchData(context, parameters) {
  try {
    const response = await get('https://api.example.com/data', {
      headers: {
        'Authorization': `Bearer ${parameters.token}`
      }
    });
    return { data: response.body };
  } catch (error) {
    return { error: error.message };
  }
}

💡 Usage Tip

• Error Handling: Always wrap sensitive code blocks with try/catch to ensure exceptions are correctly caught and handled.
• Input Validation: Strictly validate and sanitize all external inputs to prevent potential security vulnerabilities.
• Performance Optimization: Avoid performing high-cost operations in handlers as much as possible. Consider asynchronous processing and parallel execution.
• Documentation: Provide detailed documentation for each tool, including input parameters, output formats, and possible error scenarios.

By following these best practices, you can build an efficient, secure, and easily maintainable JS MCP server.