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Gemini CLI

Firefox DevTools MCP for Gemini CLI

io.github.mozilla/firefox-devtools-mcp

Control and debug Firefox: navigate, fill forms, inspect network and console, profile.

client:Gemini CLI transport:stdio runtime:npm

Install Firefox DevTools MCP in Gemini CLI

~/.gemini/settings.json · windows: %USERPROFILE%\.gemini\settings.json

Held in this page only — never stored, logged, or sent anywhere but back to your screen. 

{
  "mcpServers": {
    "firefox-devtools-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mozilla/firefox-devtools-mcp"
      ],
      "env": {
        "FIREFOX_HEADLESS": "<FIREFOX_HEADLESS>",
        "START_URL": "<START_URL>"
      }
    }
  }
}

Gemini expands $VAR and ${VAR} inside env values, so a secret can live in your shell rather than this file. Gemini CLI docs

Firefox DevTools MCP in other clients

Firefox DevTools MCP MCP server