MCP Servers over Streamable HTTP — Step-by-Step Guide

📝 Read the full article here: MCP Servers over Streamable HTTP (Step-by-Step)

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This repository contains a complete, working example of how to build and run an MCP (Model Context Protocol) server using Python, mcp, and FastAPI. You’ll learn how to:

• Expose tools and functions over HTTP using the MCP protocol
• Connect those tools to AI assistants like Cursor
• Use streamable HTTP as the transport
• Mount multiple MCP servers in a FastAPI app

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📁 Folder Structure

.
├── docs/                        # Diagrams and assets (e.g., mcp-client-server.png)
├── fastapi_example/            # Example mounting multiple MCP servers in FastAPI
│   ├── echo_server.py          # A server exposing a simple echo tool
│   ├── math_server.py          # A server exposing a math tool
│   └── server.py               # FastAPI app that mounts both echo and math servers
├── .gitignore
├── .python-version             # Python version (for tools like pyenv or uv)
├── pyproject.toml              # Project config and dependencies
├── readme.md                   # You're here!
├── runtime.txt                 # Python runtime for platforms like Render
├── server.py                   # Basic standalone MCP server using Tavily search
├── uv.lock                     # Lockfile for uv dependency manager

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🛠 Quickstart

1. Install uv (recommended Python package manager)

curl -LsSf https://astral.sh/uv/install.sh | sh

2. Install dependencies and set up environment

uv venv && source .venv/bin/activate
uv pip install -r pyproject.toml

3. Run the basic MCP server This uses the Tavily API to expose a simple web_search tool.

uv run server.py

4. Run the FastAPI app with multiple MCP servers

uv run fastapi_example/server.py

This will mount:

• http://localhost:8000/echo/mcp/
• http://localhost:8000/math/mcp/

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🧪 Debug with MCP Inspector

1. Install CLI support

uv add 'mcp[cli]'

2. Launch the inspector

uv run mcp dev server.py

Then go to: http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=...

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🔌 Connect to Cursor

In Cursor, add your MCP server under Chat Settings > MCP Servers:

{
  "mcpServers": {
    "tavily": {
      "url": "http://localhost:8000/mcp/"
    }
  }
}

✅ Note: You must include the trailing / in the URL.

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