Running Your MCP Server with FastMCP v2.0

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.

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✅ Prerequisites

Assumes:

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

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🚀 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

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🛠️ 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.

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🔧 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

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✅ 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.

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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/[email protected] for best compatibility.