Firefox Devtools MCP Server

Model Context Protocol (MCP) server for Firefox DevTools automation

Local serverstdio

What is the Firefox Devtools MCP MCP server?

Connect Firefox Devtools MCP to Claude, Cursor or any other MCP client and it stops being a tab you switch to. Model Context Protocol (MCP) server for Firefox DevTools automation. The firefox devtools mcp mcp server is what makes that connection.

What the server does

Model Context Protocol server for automating Firefox via WebDriver BiDi (through Selenium WebDriver). Works with Claude Code, Claude Desktop, Cursor, Cline and other MCP clients.

Installation

Installation goes through your MCP client rather than a global install: point it at @mozilla/firefox-devtools-mcp on npm and it is fetched when the client starts. The copy-paste blocks for Claude Desktop, Claude Code and Cursor are further down this page.

Credentials and setup notes

Configuration is passed through the environment: START_URL. Treat anything key-shaped as a real credential — scope it to the minimum the server needs, and rotate it if it ever lands in a shared config.

  • Node.js ≥ 20.19.0 - Firefox 100+ installed (auto‑detected, or pass --firefox-path)

Where it fits

This sits in the developer tooling group, where several servers overlap in what they claim to do but differ sharply once you actually set them up. It is maintained by mozilla; worth a glance at recent repository activity before you build anything load-bearing on it.

This entry was verified against Firefox Devtools MCP's own documentation before publication; SyncDev keeps the directory reviewed rather than auto-generated.

Worth knowing first

  • It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
  • Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
  • Keep per-call confirmation enabled while you learn its behaviour; it is the cheapest safeguard you have.

How to install the Firefox Devtools MCP MCP server

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

Add to claude_desktop_config.json, then restart Claude Desktop.

Configuration

  • Node.js ≥ 20.19.0 - Firefox 100+ installed (auto‑detected, or pass --firefox-path)
VariableDescriptionRequired
START_URLEndpoint or connection string the server talks to.Yes

Frequently asked questions

It connects Firefox Devtools MCP to MCP-compatible AI assistants such as Claude and Cursor. Instead of copying data back and forth by hand, the assistant works with Firefox Devtools MCP directly.