Firefox DevTools MCP

Install from the author’s instructions

Before connecting

• Install Node.js and a local Firefox version meeting the README’s requirements.
• Use a dedicated Firefox profile; the agent can access the websites and sessions available to that profile.

{
  "mcpServers": {
    "firefox-devtools": {
      "command": "npx",
      "args": [
        "-y",
        "@mozilla/firefox-devtools-mcp@latest",
        "--headless",
        "--viewport",
        "1280x720"
      ],
      "env": {
        "START_URL": "about:blank"
      }
    }
  }
}

Sources: Author README · Checked 2026-10-15.

The author’s example uses a local headless browser. Review the tool presets before connecting; the default basic preset includes script evaluation.

Sources: Author README · Checked 2026-10-15.

Tools and capabilities

Sources: Author README · Checked 2026-10-15.

Workflow examples

Suggested prompts for your own client. These are examples, not recorded tool executions.

Open my local development page in Firefox, take a page snapshot, and report any console errors together with the failing network requests.

Inspect the form on my test page, explain its labels and interaction flow, and suggest a reproducible accessibility check.

Sources and verification

Publisher-owned README and public GitHub metadata reviewed on 2026-10-15. Installation examples are transcribed from the author. No third-party package was installed or executed, and no account or hosted MCP endpoint was connected.

Recent activity refers to the repository push timestamp. It does not establish the product’s original release date. Stars are a dated snapshot of the entire repository.

1. GitHub repository metadataVerified 2026-10-15
2. Author READMEVerified 2026-10-15

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