What is web-quality-skills AGENTS.md?

A set of instructions for coding agents working on Web Quality Skills, a collection of checks for website speed, accessibility, search visibility, and browser behavior. It explains the project layout and how to route live audits through available browser tools.

Use it to run or direct Lighthouse and Chrome DevTools checks, study performance traces, and find the right project files or skill format when contributing to Web Quality Skills.

It gives agents a shared way to inspect website quality and interpret results. It also helps separate lab measurements from real-user data, so one test is not mistaken for a complete picture.

How addyosmani/web-quality-skills configures Codex and OpenCode

About the project

Web Quality Skills is a collection of agent skills for measuring and improving website performance, accessibility, search optimization, and browser usability. Developers use it with any web framework to run Lighthouse and Chrome DevTools checks, analyze Core Web Vitals and CrUX data, and apply WCAG and SEO guidance. The catalogue entries are the project's own skills, instructions, and plugin for agent-assisted web-quality work.

addyosmani/web-quality-skills · 2,758 stars · on GitHub

Reuse

Borrowing it

Nothing to install: this file belongs to addyosmani/web-quality-skills. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/addyosmani/web-quality-skills/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/addyosmani/web-quality-skills

Made for: Codex, OpenCode.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/addyosmani/web-quality-skills/agents-md.svg)](https://agentmods.dev/instructions/addyosmani/web-quality-skills/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/addyosmani/web-quality-skills/agents-md"><img src="https://agentmods.dev/badge/instructions/addyosmani/web-quality-skills/agents-md.svg" alt="Measured on agentmods" height="20"></a>

Per session 1,470 This file is loaded in full into every session.

When invoked 1,470 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.01470	$0.01470
Opus 5	$0.00735	$0.00735
Sonnet 5	$0.00294	$0.00294
Haiku 4.5	$0.00147	$0.00147

Measured 8d ago against content hash 1cb4eceec0ff, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

web-quality-skills 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 8d 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.

AGENTS.md · 223 lines

How it starts

The opening of the file, as written. The whole thing — 223 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

This file provides guidance to AI coding agents (Claude Code, Cursor, Copilot, etc.) when working with code in this repository.

Project overview

Web Quality Skills is a measurement-first collection of Agent Skills for Google Lighthouse, Chrome DevTools, Core Web Vitals, accessibility, SEO, best practices, and agentic browsing. Skills follow the Agent Skills specification.

Live audit routing

Prefer capabilities over provider-specific tool names. Record a browser performance trace and analyze focused insights; with Chrome DevTools MCP, use performance_start_trace and performance_analyze_insight.
Run live Lighthouse audits for Accessibility, SEO, Best Practices, and Agentic Browsing; with Chrome DevTools MCP, use lighthouse_audit. It intentionally excludes performance.
Read skills/performance/references/MEASUREMENT.md for field/lab fallbacks, CrUX scope, and repeatable comparisons.
Treat a single trace or PerformanceObserver result as a lab observation, not real-user data. When no page can run, label performance findings as source hypotheses.

Directory structure

web-quality-skills/
├── README.md                    # Project documentation
├── AGENTS.md                    # This file
├── LICENSE                      # MIT License
└── skills/
    ├── web-quality-audit/       # Comprehensive audit skill
    │   ├── SKILL.md
    │   ├── scripts/
    │   └── references/
    ├── performance/             # Performance optimization
    │   ├── SKILL.md
    │   ├── scripts/
    │   └── references/
    ├── accessibility/           # Accessibility guidelines
    │   ├── SKILL.md
    │   ├── scripts/
    │   └── references/
    ├── seo/                     # SEO best practices
    │   ├── SKILL.md
    │   ├── scripts/
    │   └── references/
    ├── best-practices/          # General best practices
    │   ├── SKILL.md
    │   ├── scripts/
    │   └── references/
    └── core-web-vitals/         # CWV-specific optimization
        ├── SKILL.md
        ├── scripts/
        └── references/

Read the full file on GitHub · 223 lines

Changes

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.

8d ago First seen · 223 lines · 1,470 tokens per session scan A 1cb4eceec0ff

Subscribe to this mod's changes

web-quality-skills AGENTS.md is an instructions file published in the GitHub repository addyosmani/web-quality-skills (2,758 stars, last pushed 14d ago), licensed MIT. It adds 1,470 tokens to every session, about $0.0073 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 2026-08-30.

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