Borrowing it
Nothing to install: this file belongs to femto/mcp-chrome. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/femto/mcp-chrome/master/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/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/instructions/femto/mcp-chrome/agents-md"><img src="https://agentmods.dev/badge/instructions/femto/mcp-chrome/agents-md.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00250 | $0.00250 |
| Opus 5.5 | $0.00100 | $0.00100 |
| Sonnet 5.5 | $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 2mo 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.
- 2mo 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 (12 stars, last pushed 1mo ago), licensed MIT. It adds 250 tokens to every session, about $0.0010 per session on Opus 5.5. 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.
mcp-chrome AGENTS.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| mcp-chrome AGENTS.mdfemto/mcp-chrome | Instructions file | 12 | 1mo ago | MIT | A | 250 | Codex, OpenCode |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 9,719 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | yesterday | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | yesterday | MIT | A | 4,680 | Codex, OpenCode |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 5,516 | GitHub Copilot |
| vscode copilot-instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 3,093 | GitHub Copilot |
| deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness | Instructions file | 274k | 2d ago | MIT | A | 4,313 | Codex, OpenCode |