README - Express MCP Server by jhgaylor

Express MCP Server

A stateless Model Context Protocol (MCP) server built with Express and TypeScript.

Features

Stateless MCP server implementation with modern Streamable HTTP transport
TypeScript for type safety
Express.js for HTTP handling

Requirements

Node.js 18+
npm or yarn

Installation

# Clone the repository (or download)
git clone https://github.com/your-username/sample-express-mcp-server.git
cd sample-express-mcp-server

# Install dependencies
npm install

Development

# Build the TypeScript code
npm run build

# Run in development mode with auto-reloading
npm run dev

# Run tests (when added)
npm test

Server Structure

src/
  ├── index.ts                # Main application entry point
  └── server.ts               # MCP server definition with resource, tool, and prompt

Available Functionality

This server implements a simple echo endpoint with three MCP components:

Resource: echo://{message} - Returns the message as a resource
Tool: echo - Echoes the provided message back as a tool response
Prompt: echo - Creates a user prompt with the provided message

MCP Protocol

This server implements the Model Context Protocol (MCP), a standardized way for LLMs to interact with external data and functionality. It exposes a stateless API endpoint that responds to JSON-RPC requests.

API Usage

Send a POST request to /mcp with a JSON-RPC payload:

Initialize

curl -X POST http://localhost:3001/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -H "Accept: text/event-stream" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2024-11-05",
      "capabilities": {
        "roots": {
          "listChanged": true
        },
        "sampling": {}
      },
      "clientInfo": {
        "name": "ExampleClient",
        "version": "1.0.0"
      }
    }
  }'

Call Echo Tool

curl -X POST http://localhost:3001/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -H "Accept: text/event-stream" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "echo",
      "arguments": {
        "message": "Hello, World!"
      }
    },
    "id": 1
  }'

express-mcp-server-text-extractor