firefox-devtools-mcp

MCP server · npm · ★ 529 · graded 2026-10-24Source linked

Model Context Protocol server for Firefox DevTools - enables AI assistants to inspect and control Firefox browser through WebDriver BiDi

No outside reports on file

firefox-devtools-mcp fetches arbitrary web URLs; restrict its folder reach, network access, and credentials before installing.

Based on public adoption and transparency signals as of Oct 24, 2026. Our opinion, not a code audit or security guarantee.

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What it can access

Local filesNo local folder access notedLOW
Command executionNo shell command runner notedLOW
Network reachFetches arbitrary web URLsREVIEW
CredentialsNo API token requiredLOW
Package sourcenpm (@mozilla/firefox-devtools-mcp-moz)PUBLIC

Inferred from this listing’s public package details and description. Check the project’s source before installing.

Install

npx -y @mozilla/firefox-devtools-mcp-moz

All setup options ↓

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About Firefox Devtools MCP

Firefox Devtools MCP is an MCP server focused on Web & browsing and Files & documents: Model Context Protocol server for Firefox DevTools - enables AI assistants to inspect and control Firefox browser through WebDriver BiDi.

It is published on npm as @mozilla/firefox-devtools-mcp-moz and hosted on GitHub at mozilla/firefox-devtools-mcp (521 GitHub stars, 5,896 weekly npm downloads). Based on its public metadata, its operational scope includes: fetches arbitrary web urls.

Setup

Check these steps against the project’s own instructions before running anything.

Run @mozilla/firefox-devtools-mcp-moz with --ignore-scripts in claude_desktop_config.json or .cursor/mcp.json:

json

{
  "mcpServers": {
    "firefox-devtools-mcp-moz": {
      "command": "npx",
      "args": ["-y", "--ignore-scripts", "@mozilla/firefox-devtools-mcp-moz"]
    }
  }
}

Why this grade

BB — Some risk signals

Signal-based grade (5/7 points): well starred on GitHub, listed in several sources, public source code. This reflects adoption and transparency, not a code review.

Popularity and upkeep

62/100

GitHub stars: 529
Weekly npm downloads: 5.9k
Listing last refreshed: 2026-10-29

These are public popularity signals, not a maintenance check. Look at the repository’s commit history and open issues.

Security reports

No reports found for this package in our research (last checked 2026-10-29).

Check a specific version →

Risks to watch for

Untrusted web content & prompt injection: Fetches arbitrary web pages or remote endpoints where hidden instructions could manipulate agent behavior. Restrict outbound domains and review tool outputs.
Dependency & version pinning: Distributed via npm (@mozilla/firefox-devtools-mcp-moz). Pin an exact release version or commit SHA rather than floating tags so upstream updates are reviewed first.

How to lower the risk

Least-privilege permissions

Give it access only to the specific folders, accounts or projects it needs, never your whole drive or admin account.
Use a separate, limited API key or login just for this tool so you can switch it off without affecting anything else.

Network isolation

Run it on a work computer or sandbox account, not one holding personal or company-sensitive data.
If your IT team can, limit which websites and services it is allowed to contact.

Monitoring

Check its activity history or logs weekly at first, and look at what it changed or sent.
Turn on alerts for new logins or unusual usage on any account it connects to.

Red flags to watch for

It asks for more access than its job requires, or prompts you to paste passwords.
It suddenly updates with new owners, or starts contacting unfamiliar websites.

Questions

How do I install Firefox Devtools MCP?

Run npx -y @mozilla/firefox-devtools-mcp-moz in your terminal, or add the server entry to your claude_desktop_config.json or .cursor/mcp.json as shown in the Setup section on this page. Full setup docs and environment variables are in github.com/mozilla/firefox-devtools-mcp.

Are there security reports about Firefox Devtools MCP?

No reports found for this package in our research (last checked 2026-10-29). Firefox Devtools MCP currently holds Grade B (Some risk signals) based on public adoption and transparency signals. Key risk areas to watch include untrusted web content & prompt injection:, dependency & version pinning:.

Is Firefox Devtools MCP actively maintained?

Firefox Devtools MCP has 529 GitHub stars and 5.9k weekly npm downloads. Our directory data was last refreshed on 2026-10-29. Check recent commit activity, release tags, and open issues at github.com/mozilla/firefox-devtools-mcp before pinning it in production.

What are alternatives to Firefox Devtools MCP?

You can compare Firefox Devtools MCP side by side with other Browser MCP servers in the Related tools section on this page, or use the Compare tool on AgentArmorHQ.

Maintain or use Firefox Devtools MCP? Show its live grade in your GitHub README, docs site, or run a check from the terminal before you install.

AgentArmorHQ Risk Grade B for Firefox Devtools MCP

GitHub README Markdown:

markdown

[![AgentArmorHQ Risk Grade for Firefox Devtools MCP](https://agentarmorhq.com/api/badge/mozilla-firefox-devtools-mcp)](https://agentarmorhq.com/skills/mozilla-firefox-devtools-mcp)

HTML embed:

html

<a href="https://agentarmorhq.com/skills/mozilla-firefox-devtools-mcp"><img src="https://agentarmorhq.com/api/badge/mozilla-firefox-devtools-mcp" alt="AgentArmorHQ Risk Grade for Firefox Devtools MCP" height="20" /></a>

Terminal check:

terminal

curl -fsSL https://agentarmorhq.com/api/cli | node --input-type=module - check "mozilla-firefox-devtools-mcp"

Share with your security lead

Need sign-off to use firefox-devtools-mcp? Copy this note for Slack, a ticket or a pull request.

### AgentArmorHQ Security Review Memo: firefox-devtools-mcp
- **Listing URL:** https://agentarmorhq.com/skills/mozilla-firefox-devtools-mcp
- **Type:** App connector
- **Risk Grade:** Grade B (Some risk signals)
- **Outside Security Advisories on File:** 0
- **Public Adoption:** 529 GitHub stars, 5.9k weekly npm downloads

#### Permission & Blast-Radius Signals
- **Local files:** No local folder access noted
- **Command execution:** No shell command runner noted
- **Network reach:** Fetches arbitrary web URLs
- **Credentials:** No API token required
- **Package source:** npm (@mozilla/firefox-devtools-mcp-moz)

#### Recommended Hardened Setup
- **Command:** `npx -y --ignore-scripts @mozilla/firefox-devtools-mcp-moz`
- **Controls:** Pin an exact version in `.mcp.json`, scope access to a single workspace folder, and use a least-privilege read-only token where supported.

_Based on public adoption and transparency signals as of Oct 24, 2026. Our opinion, not a code audit or security guarantee._

Key facts

Type: App connector
Publisher: mozilla
Source code: github.com/mozilla/firefox-devtools-mcp
Install command: npm install @mozilla/firefox-devtools-mcp-moz
Est. context load: ~700 tokens / turn (~4 tool schemas, 0.35% of 200k context)
Popularity: 529 GitHub stars, 5.9k weekly npm downloads
Last updated: 2026-10-29
Last graded: 2026-10-24

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