What is Elysia Mcp

Elysia-mcp is a Model Context Protocol (MCP) server implementation built using Bun and the Elysia web framework. It allows developers to create high-performance MCP servers that provide resources, tools, and prompts to Large Language Models (LLMs) through a standardized interface.

Use cases

Elysia-mcp can be used in various scenarios such as developing applications that require real-time communication with LLMs, creating interactive tools that utilize resources and prompts, and building high-performance servers for data processing and analysis.

How to use

To use Elysia-mcp, first ensure Bun is installed on your system. Clone the repository, install dependencies using ‘bun install’, and start the server with ‘bun start’. For production, build the project using ‘bun run build’. You can create an MCP server by importing necessary modules and defining resources, tools, and prompts as shown in the example code.

Key features

Key features of Elysia-mcp include: Server-Sent Events (SSE) transport implementation, complete MCP protocol support, high performance due to Bun’s JavaScript runtime, TypeScript support with proper type definitions, and an easy-to-use API for creating MCP-compatible servers.

Where to use

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MCP Server for Bun and Elysia

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

Features

• Server-Sent Events (SSE) transport implementation for Bun and Elysia
• Complete MCP protocol support with resources, tools, and prompts
• High-performance thanks to Bun’s JavaScript runtime
• TypeScript support with proper type definitions
• Easy-to-use API for creating MCP-compatible servers

Prerequisites

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

Installation

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

# Install dependencies
bun install

Usage

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.

Development

Project Structure

• src/index.ts - Main entry point for the server
• src/SSEElysiaTransport.ts - 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 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: "Example resource content"
    }]
  })
);

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

// Start server
app.listen(3001, () => {
  console.log("MCP Server running at http://localhost:3001");
});

Debugging

You can debug your MCP server using the MCP Inspector tool and connect through sse

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 server

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.