# Firefox DevTools MCP

> Mozilla's MCP server for Firefox: your agent browses and fills in forms, or inspects pages with the console, network, debugger and profiler.

Mozilla's own MCP server lets your agent use Firefox. It has two main uses: agentic browsing, where your agent reads pages, fills in forms and goes through multi-step flows on websites, and agent-assisted web development, where it loads the page you're working on and inspects it with Firefox's developer tools.

What you can do with it
- Open, navigate and switch between pages, and read a page's text
- Take a snapshot of the page, then click, hover, type, drag, upload files and fill in whole forms
- Take screenshots of a page or a single element, print a page to PDF and record screencasts
- List and inspect network requests, and read console messages
- Run JavaScript in the page, read script sources and set logpoints
- Start and stop the Firefox profiler
- Install and remove web extensions, and handle downloads and dialogs
- Drive Firefox for Android on a connected device

How it connects
It runs on your machine with npx @mozilla/firefox-devtools-mcp@latest, and needs Node.js 20.19 or later and Firefox 100 or later. Mozilla documents setup for Claude Code and Codex, and says it works with Claude Desktop, Cursor, Cline and other MCP clients. It's also a Gemini CLI extension, which starts it with the developer tools turned on. Flags let you run Firefox headless, set the window size, pick a Firefox profile or attach to a Firefox you already have open.

Choose what it can do
--tool-preset picks which tools it exposes: slim to browse and interact with pages, basic (the default) for regular browsing, and developer to add network, console, debugging and profiler tools. --tools lets you list exact modules instead.

Good to know
- Mozilla advises a dedicated Firefox profile, since the agent can reach whatever the browser can, including cookies and saved sessions.
- Pages can contain text written to steer the agent, so stick to sites you control or trust.
- The default basic preset includes evaluate_script; slim drops it.
- Android mode wipes all data of the Firefox app it drives before every session.

- Type: Plugin
- Made by: mozilla
- Category: Web & browser
- Formats: Local MCP, Extensions
- Version: 0.10.5
- Website: https://github.com/mozilla/firefox-devtools-mcp
- Source: https://github.com/mozilla/firefox-devtools-mcp
- Page: https://pluginboard.ai/plugins/firefox-devtools-mcp

## Works with

- Claude
- GitHub Copilot
- Cursor
- Claude Code
- Codex
- Antigravity
- Gemini CLI
- OpenClaw
- OpenCode
- Hermes Agent

## Install

You'll need:

- `FIREFOX_HEADLESS` (optional): Set to true to run Firefox without a visible window.
- `START_URL` (optional): URL to open when the server starts.

Replace each `<NAME>` placeholder with your own value.

### Claude

Add to claude_desktop_config.json:

```json
{
  "mcpServers": {
    "firefox-devtools-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mozilla/firefox-devtools-mcp@0.10.6",
        "--tool-preset",
        "developer"
      ]
    }
  }
}
```

### GitHub Copilot

Add to VS Code: vscode:mcp/install?%7B%22name%22%3A%22firefox-devtools-mcp%22%2C%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40mozilla%2Ffirefox-devtools-mcp%400.10.6%22%2C%22--tool-preset%22%2C%22developer%22%5D%7D

Run in your terminal:

```shell
code --add-mcp '{"name":"firefox-devtools-mcp","command":"npx","args":["-y","@mozilla/firefox-devtools-mcp@0.10.6","--tool-preset","developer"]}'
```

Copilot CLI:

```shell
copilot mcp add firefox-devtools-mcp -- npx -y @mozilla/firefox-devtools-mcp@0.10.6 --tool-preset developer
```

### Cursor

Add to Cursor: cursor://anysphere.cursor-deeplink/mcp/install?name=firefox-devtools-mcp&config=eyJjb21tYW5kIjoibnB4IiwiYXJncyI6WyIteSIsIkBtb3ppbGxhL2ZpcmVmb3gtZGV2dG9vbHMtbWNwQDAuMTAuNiIsIi0tdG9vbC1wcmVzZXQiLCJkZXZlbG9wZXIiXX0%3D

Add to .cursor/mcp.json:

```json
{
  "mcpServers": {
    "firefox-devtools-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mozilla/firefox-devtools-mcp@0.10.6",
        "--tool-preset",
        "developer"
      ]
    }
  }
}
```

### Claude Code

Run in your terminal:

```shell
claude mcp add firefox-devtools-mcp -- npx -y @mozilla/firefox-devtools-mcp@0.10.6 --tool-preset developer
```

### Codex

Run in your terminal:

```shell
codex mcp add firefox-devtools-mcp -- npx -y @mozilla/firefox-devtools-mcp@0.10.6 --tool-preset developer
```

### Antigravity

Add to ~/.gemini/config/mcp_config.json:

```json
{
  "mcpServers": {
    "firefox-devtools-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mozilla/firefox-devtools-mcp@0.10.6",
        "--tool-preset",
        "developer"
      ]
    }
  }
}
```

### Gemini CLI

Run in your terminal:

```shell
gemini extensions install https://github.com/mozilla/firefox-devtools-mcp
```

### OpenClaw

In a terminal: Run openclaw mcp add firefox-devtools-mcp --command npx, with --arg before each argument (-y @mozilla/firefox-devtools-mcp@0.10.6 --tool-preset developer) and --env NAME=value for each variable it needs.

### OpenCode

Run in your terminal:

```shell
opencode mcp add firefox-devtools-mcp -- npx -y @mozilla/firefox-devtools-mcp@0.10.6 --tool-preset developer
```

### Hermes Agent

Add to ~/.hermes/config.yaml:

```json
{
  "mcp_servers": {
    "firefox-devtools-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mozilla/firefox-devtools-mcp@0.10.6",
        "--tool-preset",
        "developer"
      ]
    }
  }
}
```

---
From Pluginboard (https://pluginboard.ai).