Elysia MCP

🚀 MCP Server Implemented with Bun and Elysia

This project is an implementation of the Model Context Protocol (MCP) server using the Bun and Elysia web frameworks. It enables you to create high - performance MCP servers that expose resources, tools, and prompts to large language models (LLMs) through a standardized interface.

🚀 Quick Start

To get started with this MCP server, make sure you meet the prerequisites and follow the installation steps. Then you can start the server and explore its features.

✨ Features

• Server - Sent Events (SSE) transport implemented with Bun and Elysia.
• Full support for the MCP protocol, including resources, tools, and prompts.
• High performance thanks to Bun's JavaScript runtime.
• TypeScript support with correct type definitions.
• An easy - to - use API for creating MCP - compatible servers.

📦 Installation

Prerequisites

• Bun installed on your system.
• Basic familiarity with TypeScript and Elysia.

Steps

# Clone the repository
git clone <your-repo-url>
cd mcp-server

# Install dependencies
bun install

💻 Usage Examples

Starting the Server

# Start the server
bun start

# Start with hot - reloading for development
bun dev

Building for Production

# Build for production
bun run build

This will create a minified Node.js - compatible build in the dist directory.

Project Structure

• src/index.ts - The main entry point of the server.
• src/SSEElysiaTransport.ts - The SSE transport implementation for Bun and Elysia.

Creating an MCP Server

import { McpServer, ResourceTemplate } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
import { SSEElysiaTransport } from "./SSEElysiaTransport";
import { Elysia } from "elysia";

// Create an MCP server
const server = new McpServer({
  name: "my-mcp-server",
  version: "1.0.0"
});

// Add resources, tools, and prompts
server.resource(
  "example", 
  "example://resource", 
  async (uri) => ({
    contents: [{
      uri: uri.href,
      text: "示例资源内容"
    }]
  })
);

// Create an Elysia application
const app = new Elysia()
  .get("/", () => "MCP 服务器")
  .get("/sse", async (context) => {
    try {
      // Create a transport
      const transport = new SSEElysiaTransport("/messages", context);
      
      // Store the transport
      const sessionId = transport.sessionId;
      // ... Store the transport in a map
      
      // Connect to the MCP server
      await server.connect(transport);
      
      return;
    } catch (error) {
      // Handle errors
    }
  })
  .post("/messages", async (context) => {
    // Handle incoming messages
  });

// Start the server
app.listen(3001, () => {
  console.log("MCP 服务器在 http://localhost:3001 运行");
});

Debugging

You can use the MCP monitor tool and connect via SSE for debugging.

npx @modelcontextprotocol/inspector

This will open a web interface where you can:

• List available resources, tools, and prompts.
• Test calling tools and retrieving resources.
• Inspect the communication between the client and the server.

Contribution

Contributions are welcome! Feel free to submit a Pull Request.

📄 License

This project is released under the MIT License. See the LICENSE file for details.