Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
git clone --depth 1 https://github.com/mozilla/firefox-devtools-mcpWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/plugins/mozilla/firefox-devtools-mcp/gemini-extension)<a href="https://agentmods.dev/plugins/mozilla/firefox-devtools-mcp/gemini-extension"><img src="https://agentmods.dev/badge/plugins/mozilla/firefox-devtools-mcp/gemini-extension/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/plugins/mozilla/firefox-devtools-mcp/gemini-extension"><img src="https://agentmods.dev/badge/plugins/mozilla/firefox-devtools-mcp/gemini-extension.svg" alt="Reviewed on agentmods" width="80" height="20"></a>Grade A, and why
firefox-devtools-mcp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
The source is not reproduced here
A licence we could not identify
The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.
What ships with it
19 files beside gemini-extension.json in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- scripts/_helpers/page-loader.js 3.4 KB runs code
- scripts/build-mcpb.mjs 2.1 KB runs code
- scripts/demo-server.js 9.7 KB runs code
- scripts/generate-moz-package.mjs 1.2 KB runs code
- scripts/generate-tools-doc.ts 5.8 KB runs code
- scripts/publish-moz-package.mjs 1.6 KB runs code
- scripts/setup-mcp-config.js 9.3 KB runs code
- scripts/sync-manifest-versions.mjs 1.4 KB runs code
- scripts/test-bidi-devtools.js 15 KB runs code
- scripts/test-closed-window.js 6.2 KB runs code
- scripts/test-console.js 5.0 KB runs code
- scripts/test-dialog.js 3.7 KB runs code
- scripts/test-firefox-temp.js 421 B runs code
- scripts/test-input-tools.js 8.2 KB runs code
- scripts/test-lifecycle-hooks.js 4.6 KB runs code
- scripts/test-mozlog.js 3.6 KB runs code
- scripts/test-navigation.js 1.6 KB runs code
- scripts/test-privileged-context.js 3.5 KB runs code
- scripts/test-screenshot.js 7.3 KB runs code
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- today Changed ab21a8593dfc
- 7d ago Changed 3d8273b66c60
- 24d ago First seen · 20 lines scan A 3e837e910ae4
firefox-devtools-mcp is a plugin published in the GitHub repository mozilla/firefox-devtools-mcp (494 stars, last pushed today), with no licence file. Its token cost is not measured: this kind of file is read by the harness, not the model. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-23.
Other plugins, from other repositories
chrome-devtools-mcp
Reliable automation, in-depth debugging, and performance analysis in Chrome using Chrome DevTools and Puppeteer.
chrome-devtools-mcp
MCP configuration declaring 1 server: chrome-devtools.
devcdp
Real Chrome DevTools access for Claude: console, network, DOM, source maps, breakpoints and live variables, plus guidance on when to use each.
devcdp
Real Chrome DevTools access for Gemini CLI: console, network, DOM, source maps, breakpoints and live variables.
oneskills
OneScience / OneSkills skills for AI-native scientific research workflows, coding, runtime submission, debugging, and environment setup.
mcp-migration
Diagnose and carry out the migration of an MCP server to the 2026-07-28 specification. Runs a deterministic rule engine over the code, then walks the remediation per finding: stateless transport, OAuth 2.1, the deprecated capabilities, and the SDK v2 rename.