Example MCP Server (Streamable HTTP)

A minimal MCP server built on the official Python SDK (mcp==2.0.0), running over Streamable HTTP so it can live in a container and be reached over the network.

It ships with two demo tools (echo, add) and one resource (time://now) so you have something to test against immediately — replace them with your own.

Run it

docker compose up -d --build
docker compose logs -f mcp-server

The server listens on http://localhost:8000/mcp.

Test it without a client

curl -i -X POST http://localhost:8000/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"test","version":"0.1"}}}'

The response headers include mcp-session-id — reuse it in an Mcp-Session-Id header on subsequent calls (tools/list, tools/call, resources/read, etc.) once you've sent a notifications/initialized message.

Point a client at it

Any MCP client that supports Streamable HTTP just needs the URL: http://localhost:8000/mcp (or your host's address/port if not running locally).

Add your own tools

@mcp.tool()
def my_tool(arg: str) -> str:
    """This docstring becomes the tool description the model sees."""
    return do_something(arg)

Resources (@mcp.resource("scheme://path")) and prompts (@mcp.prompt()) follow the same pattern. Restart the container after changes:

docker compose up -d --build

Notes

• MCP_HOST / MCP_PORT env vars control what the server binds to inside the container — leave MCP_HOST=0.0.0.0 or it won't be reachable from outside the container.
• This has no authentication. Fine for local/dev use behind localhost:8000; if you expose it beyond your machine, put it behind a reverse proxy or gateway that handles auth (or use the SDK's built-in OAuth support via token_verifier/auth_server_provider).
• The old from mcp.server.fastmcp import FastMCP import path some tutorials still show is gone as of mcp==2.0.0 — it's now from mcp.server import MCPServer.