ZichengMa/echo-mcp-server

FastMCP Echo Server

A minimal Model Context Protocol (MCP) server built with FastMCP that exposes a single echo tool. Useful as a simple example or for debugging MCP client integrations.

Features

• Single echo(text: str) -> str tool that returns the input
• Runs over SSE transport on 0.0.0.0:8080
• Includes a small test client (test.py) to validate the server

Requirements

• Python 3.10+

Setup

You can use either pip or uv.

Option A: pip (recommended for simplicity)

python -m venv .venv
source .venv/bin/activate  # Windows: .venv\Scripts\activate
pip install -U pip
pip install "fastmcp>=0.1.0" "uvicorn>=0.30.0" "httpx>=0.27.0" "mcp>=1.0.0"

Option B: uv (if you use uv)

If you have uv installed and want to use the project lockfile:

uv sync

Run the server

python main.py

The server listens on http://0.0.0.0:8080 and serves MCP over Server‑Sent Events (SSE) at /sse.

Test the server

A simple async test client is provided in test.py.

# In a separate terminal while the server is running
python test.py http://localhost:8080

You should see the tool list and a successful echo call.

Project structure

• main.py — FastMCP server exposing the echo tool
• test.py — script that connects over SSE and verifies the tool
• pyproject.toml — project metadata and dependencies
• uv.lock — lockfile for uv users

Configuration

Default host/port and transport are set in main.py. Adjust as needed:

mcp.run(
    transport="sse",
    host="0.0.0.0",
    port=8080,
)

Notes

• This example does not implement authentication and is intended for local/testing use.
• Make sure your client supports MCP over SSE when connecting.