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.
npx agentmods add instructions/femto/mcp-chrome/agents-mdgit clone --depth 1 https://github.com/femto/mcp-chromeWrote 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/instructions/femto/mcp-chrome/agents-md)<a href="https://agentmods.dev/instructions/femto/mcp-chrome/agents-md"><img src="https://agentmods.dev/badge/instructions/femto/mcp-chrome/agents-md.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00250 | $0.00250 |
| Opus 5 | $0.00125 | $0.00125 |
| Sonnet 5 | $0.00050 | $0.00050 |
| Haiku 4.5 | $0.00025 | $0.00025 |
Grade A, and why
mcp-chrome AGENTS.md 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 5d ago.
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.
What it actually says
Chrome MCP Server - Build Instructions
Chrome Extension Build
Local Development (with fixed extension ID)
cd app/chrome-extension
pnpm wxt build
This uses the key from .env.local to maintain a consistent extension ID (gkgkeiahoaihgefckmjckmennckgaege) for local testing.
Chrome Web Store Release (without key)
cd app/chrome-extension
CHROME_EXTENSION_KEY= pnpm wxt build
Or temporarily rename/delete .env.local before building.
The Chrome Web Store manages its own extension key, so the manifest must not contain a key field when publishing.
Package for Upload
cd app/chrome-extension/.output
zip -r chrome-mcp-server-x.x.x.zip chrome-mv3
Native Server Build
cd app/native-server
pnpm build
Shared Package Build
cd packages/shared
pnpm build
Full Rebuild (all packages)
pnpm -r build
Version Update
Update version in app/chrome-extension/package.json before building for release.
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.
- 5d ago First seen · 55 lines · 250 tokens per session scan A 1827508bfaf7
mcp-chrome AGENTS.md is an instructions file published in the GitHub repository femto/mcp-chrome (10 stars, last pushed 1mo ago), licensed MIT. It adds 250 tokens to every session, about $0.0013 per session on Opus 5. 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 2026-08-31.
Other instructions, from other repositories
Browser4 CLAUDE.md
Claude Code instructions for platonai/Browser4, covering browser4 — project context for claude, architecture, key dispatch chain (cli → browser), batch commands and e2e test structure.
cc-websearch CLAUDE.md
Claude Code instructions for Djarvur/cc-websearch, covering project, constraints, technology stack, what not to add and conventions.
fix-quera AGENTS.md
Instructions for AlirezaKeshavarz83/fix-quera, covering agent guidance, project shape, visual style, quera page data findings and compatibility findings.
sniff AGENTS.md
AGENTS.md instructions for Aboudjem/sniff, covering agents.md: sniff, what this repo is, how an agent should use sniff, handling the playwright setup gate and finding output schema.
fast-browser CLAUDE.md
Claude Code instructions for m4ttstack/fast-browser, covering fast browser plugin, where a change belongs, fork branch: use fast-browser-runtime, releasing a new runtime and re-pinning this repo: use the script.
sendblue-browser-use AGENTS.md
Instructions for sendblue-api/sendblue-browser-use, covering agents.md — sendblue-browser-use, what this repo is, setup, common commands and health (no auth).