Borrowing it
Nothing to install: this file belongs to uiuing/browser-agent. 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/uiuing/browser-agent/main/AGENTS.mdgit clone --depth 1 https://github.com/uiuing/browser-agentWrote 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/uiuing/browser-agent/agents-md)<a href="https://agentmods.dev/instructions/uiuing/browser-agent/agents-md"><img src="https://agentmods.dev/badge/instructions/uiuing/browser-agent/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/uiuing/browser-agent/agents-md"><img src="https://agentmods.dev/badge/instructions/uiuing/browser-agent/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 | $0.01806 | $0.01806 |
| Opus 5.5 | $0.00722 | $0.00722 |
| Sonnet 5.5 | $0.00361 | $0.00361 |
| Haiku 4.5 | $0.00181 | $0.00181 |
Grade A, and why
browser-agent 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.
How it starts
The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md — guide for AI coding agents
Browser Agent is an open-source MV3 Chrome extension: the agent harness for the browser. Bring any model; the harness provides the agent loop, context assembly, tools, guardrails, memory and observability — and every claimed page effect is verified against page truth. TypeScript strict, pnpm monorepo, no backend.
Terminology: harness = the whole product. engine (src/engine/) = the page-action runtime (perception/grounding/execute/verify/failure handling), exposed to the loop as the page_act tool.
Setup & commands
pnpm install # workspace root; runs `wxt prepare` for the extension
pnpm build # fixtures + extension build, then typechecks bench/e2e
pnpm dev:ext # extension dev server (WXT hot reload)
pnpm --filter @browser-agent/extension compile # tsc --noEmit for the extension only
pnpm --filter @browser-agent/extension zip # release zip → packages/extension/.output/browser-agent-<ver>-chrome.zip
Extension build output: packages/extension/.output/chrome-mv3 (load unpacked in Chrome).
Tests — run these before claiming done
pnpm test:engine # fast, headless-DOM checks of the engine (perception/grounding/verify/heal)
pnpm test:e2e # full extension e2e with the scripted MockProvider; needs Playwright Chromium
pnpm shots # screenshot walkthrough of all UI surfaces → shots/
Notes for e2e:
- e2e builds the extension itself with
VITE_USE_MOCK=1(routes to a deterministic scripted mock — no API key needed). Never ship or commit a mock build;pnpm buildat root always produces the production build. - Real-model suites (
test:real,test:sitesinpackages/e2e) readREAL_BASE/REAL_KEY/REAL_MODELenv vars (never hardcode keys) and always rebuild in production mode;SKIP_BUILD=1reuses the previous build. - On Windows sandboxes, Playwright may need
PLAYWRIGHT_BROWSERS_PATHpointing at the localms-playwrightcache. - Chrome 137+ requires
--disable-features=DisableLoadExtensionCommandLineSwitchto load extensions from CLI (the e2e launcher already handles it).
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 · 89 lines · 1,806 tokens per session scan A dd789a274df8
browser-agent AGENTS.md is an instructions file published in the GitHub repository uiuing/browser-agent (56 stars, last pushed 3mo ago), licensed MIT. It adds 1,806 tokens to every session, about $0.0072 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 2026-08-30.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deno copilot-instructions.md
Copilot instructions for denoland/deno, covering deno development guide for github copilot, network access, high level overview, key directories and key files to understand first.