Running Your MCP Server with FastMCP v2.0

This guide walks you through how to run your MCP server using FastMCP v2.0 and install it for use with Claude Desktop.

✅ Prerequisites

Assumes:

• Your environment is already set up
• Your server code (e.g., server.py) is complete and ready to run

🚀 Running the Server

1. Install FastMCP (if not already installed)

It's recommended to use uv:

uv pip install fastmcp

If you don’t have uv, you can install it via Homebrew (macOS):

brew install uv

Or use pip directly:

pip install fastmcp

2. Run Your Server

Using FastMCP’s run command:

fastmcp run server.py

If your script uses the standard entry point:

if __name__ == "__main__":
    mcp.run()

Then you can also simply:

python server.py

🛠️ Installing Server for Claude Desktop

1. Install the Server

This command prepares your server for Claude Desktop integration:

fastmcp install server.py

2. Restart Claude Desktop

After installing, restart Claude Desktop to load your newly installed server.

🔧 Additional Tips

Specify Dependencies

Declare additional packages when instantiating FastMCP:

mcp = FastMCP("My Server", dependencies=["pandas", "numpy"])

Set Environment Variables

Pass env variables during installation:

fastmcp install server.py -e API_KEY=your_api_key

Use a .env File

Load environment configuration from a file:

fastmcp install server.py -f .env

✅ Example Claude Prompt

If you’ve defined a tool like add, you can talk to Claude like this:

"Please add 5 and 7."

Claude will then use the MCP server to calculate the result.

For more info, visit: https://github.com/jlowin/fastmcp

ℹ️ Reminder: If you want to use debugging tools like mcp-inspector, you should use @modelcontextprotocol/inspector@0.9.0 for best compatibility.