Hello World MCP Server

A learning project for the Model Context Protocol using the TypeScript SDK (@modelcontextprotocol/sdk v1.27.x). Demonstrates two transport modes with a single hello_world tool.

Setup

npm install

Transport Modes

stdio — local / process-spawned

The client spawns the server as a subprocess and communicates over stdin/stdout. Best for local dev and desktop app integrations (e.g. Kiro, Claude Desktop).

npm start

To wire it into Kiro, add to .kiro/settings/mcp.json:

{
  "mcpServers": {
    "hello-world": {
      "command": "node",
      "args": ["<absolute-path>/src/mcp-stdio.js"],
      "disabled": false
    }
  }
}

Streamable HTTP — remote / hosted

An Express server exposing the MCP protocol over HTTP with session management. Best for shared or cloud deployments.

npm run start:hosted

Listens on http://localhost:3000/mcp (override with PORT env var).

Endpoints:

• POST /mcp — initialize session + send requests
• GET /mcp — server→client SSE stream (existing session)
• DELETE /mcp — end session
• GET /healthz — health check

Test client

A small script that connects to the hosted server, lists tools, and calls hello_world:

# start the hosted server first, then in another terminal:
node test-streamable-http.js

Project Structure

src/
  mcp-stdio.js             # stdio transport (McpServer)
  mcp-streamable-http.js   # Streamable HTTP transport (McpServer + Express)
test-streamable-http.js    # test client for the hosted server

SDK Reference

Both servers use the high-level McpServer API from @modelcontextprotocol/sdk/server/mcp.js. Key concepts:

• server.registerTool(name, config, handler) — register a tool (capabilities auto-declared)
• server.registerResource(name, uri, config, handler) — expose read-only data
• server.registerPrompt(name, config, handler) — reusable prompt templates
• server.connect(transport) — bind to a transport and start serving

Docs: https://github.com/modelcontextprotocol/typescript-sdk/tree/v1.x