Easy MCP Server

An MCP server implementation using Streamable HTTP transport (Protocol Version 2025-11-25).

Features

• Protocol: MCP Streamable HTTP (2025-11-25)
• Transport: HTTP POST/GET/DELETE
• Tools: hello-world, add_two_numbers (plus Copilot aliases add-two-numbers, welcome, greeting)
  • add_two_numbers / add-two-numbers: accept { "prompt": string }, extract the first two numbers, return the sum
• Monitoring: Health and Info endpoints

Setup

1. Install Dependencies

   npm install

2. Build

   npm run build

3. Start Server

   npm start

   The server runs on http://127.0.0.1:8080 by default.

API Endpoints

• POST /mcp: JSON-RPC requests (Initialize, Call Tool, etc.)
• GET /mcp: Server-Sent Events (SSE) stream
• DELETE /mcp: Terminate session
• GET /health: Health check
• GET /info: Server information

Tools (Names + Parameters)

These tool contracts are intentionally explicit so MCP clients (including Copilot plugins) can call tools directly instead of relying on ad-hoc parsing.

add_two_numbers (preferred) / add-two-numbers (alias)

• Purpose: Add two numbers extracted from the full user prompt.
• Input:
  • { "prompt": string }
• Behavior:
  • Extracts the first two numbers from prompt (supports negatives and decimals).
  • Errors if fewer than 2 numbers are present.

Client guidance:

• If the user message contains at least two numbers and asks to add/sum/plus/total, call this tool.
• Pass the full user message verbatim as prompt (example: please add following number 10 and 7).
• Output:
  • structuredContent: { "sum": number }
  • content: text containing the sum

Example JSON-RPC tools/call:

{
   "jsonrpc": "2.0",
   "id": 2,
   "method": "tools/call",
   "params": {
      "name": "add_two_numbers",
      "arguments": { "prompt": "please add 10 and 20" }
   }
}

hello-world

• Purpose: Return the welcome message from resources/hello-world/welcome.md.
• Aliases: welcome, greeting (same behavior as hello-world)
• Input:
  • {} (no parameters)
• Output:
  • structuredContent: { "message": string, "mcpSdkVersion": string, "clientName": string, "clientVersion": string }
  • content: text containing the welcome message plus versions

Example JSON-RPC tools/call:

{
   "jsonrpc": "2.0",
   "id": 3,
   "method": "tools/call",
   "params": {
      "name": "hello-world",
      "arguments": {}
   }
}

Sequence Diagram

sequenceDiagram
    participant Client
    participant Server

    Note over Client, Server: Initialization
    Client->>Server: POST /mcp (method: initialize)
    Server-->>Client: 200 OK (Mcp-Session-Id: uuid)

    Note over Client, Server: Connection
    Client->>Server: GET /mcp (Header: Mcp-Session-Id)
    Server-->>Client: 200 OK (SSE Stream Open)

    Note over Client, Server: Tool Execution
    Client->>Server: POST /mcp (method: tools/call)
    Server-->>Client: 202 Accepted
    Server->>Client: SSE Event (jsonrpc response)

    Note over Client, Server: Termination
    Client->>Server: DELETE /mcp
    Server-->>Client: 200 OK

Loading

Testing

Run unit tests:

npm test

Directory Structure

• src/core/: Core server logic and transport.
• src/tools/: Tool implementations.
• src/index.ts: Entry point.