Firefox DevTools MCP

Firefox DevTools MCP is a local MCP server: Control and debug Firefox: navigate, fill forms, inspect network and console, profile. Install it from npm as @mozilla/firefox-devtools-mcp.

Claude CodeCodexAntigravity

commandprompt

Terminal

claude mcp add firefox-devtools-mcp -e FIREFOX_HEADLESS=... -e START_URL=... -- npx -y @mozilla/firefox-devtools-mcp

Run in your project folder. Add --scope user to use it everywhere.

Add to claude_desktop_config.json or .cursor/mcp.json.

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

Fill in the environment variables with your own credentials.

• Runtime: Node.js 18+ (runs with npx).
• MCP client: Claude Code, Codex, Antigravity, Claude Desktop, Cursor or any other client that speaks MCP over stdio.
• Environment variables: FIREFOX_HEADLESS, START_URL