Gemini CLI¶

Wire justpen-browser-mcp into Gemini CLI.

Prerequisites¶

Gemini CLI installed and authenticated with MCP support enabled
justpen-browser-mcp installed and on PATH (see Install)

Registration¶

Add to your Gemini CLI MCP config (see upstream Gemini CLI docs for the canonical config file location):

{
  "mcpServers": {
    "justpen-browser": {
      "command": "justpen-browser-mcp"
    }
  }
}

Running outside the install venv¶

If Gemini CLI runs outside the venv where justpen-browser-mcp is installed, use an explicit interpreter path:

{
  "mcpServers": {
    "justpen-browser": {
      "command": "/absolute/path/to/.venv/bin/python",
      "args": ["-m", "justpen_browser_mcp"]
    }
  }
}

Sanity check¶

After registering, list MCP servers / tools from within Gemini CLI. The justpen-browser server should appear with its lifecycle, navigation, and interaction tools.

Common pitfalls¶

command not found — the justpen-browser-mcp script is not on the PATH Gemini CLI sees. Use the absolute-path form above.
Headless mode — browser_create_instance defaults to headless=true. Pass headless=false to the tool call when you want to watch the browser for debugging.
Transport selection — these examples use stdio. The server also supports HTTP when started with --transport http; configure your client for Streamable HTTP at http://127.0.0.1:8931/mcp to use it. See Run the server, including its warning about the lack of built-in authentication.

Reference¶

Canonical Gemini CLI MCP config docs: see the upstream Gemini CLI documentation for the up-to-date config schema and config-file location.