Call tools from MCP clients

stdio (default)

When configuring your MCP client using the stdio transport, you need to ensure that the MCP server is called using the right version of python and within the correct working directory. For example, let’s pretend this is your setup:

• Your virtual environment is located at /path/to/your/project/.venv
• Your project is located at /path/to/your/project
• The entrypoint to your MCP server is server.py
• One of your tools requires the MY_SECRET_KEY environment variable to be set.

Then, your MCP client’s configuration file should look like this:

{
  "mcpServers": {
    "my_server": {
      "command": "/path/to/your/project/.venv/bin/python",
      "args": ["/path/to/your/project/server.py", "stdio"],
      "env": {
        "MY_SECRET_KEY": "my-secret-value"
      }
    }
  }
}

This will ensure that the command used by the MCP client to start the MCP server is the correct version of python and that the environment variables are set correctly.

Streamable HTTP

When configuring your MCP client using the http transport, ensure the MCP server is started on the correct port and from the correct working directory. For example, if your setup is:

• Your virtual environment is located at /path/to/your/project/.venv
• Your MCP server is located at /path/to/your/project/server.py
• Your secrets are stored in the .env file

Activate the virtual environment:

source /path/to/your/project/.venv/bin/activate

run the MCP server using the http transport. The secrets will be loaded from the .env file:

uv run server.py http

Then, your MCP client’s configuration file should look like this:

{
  "mcpServers": {
    "my_server": {
      "url": "http://127.0.0.1:8000",
      "transport": "http"
    }
  }
}