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Web Quality Skills Claude skills

Six skills by Addy Osmani for auditing and fixing web performance, Core Web Vitals, accessibility, SEO and best practices, built around Lighthouse.

addyosmani/web-quality-skills 6 skills Design & frontendSEOCode review & quality
Our verdict Recommended

Well-written, MIT-licensed guidance from a known web performance author that insists on measuring before fixing; just note the repo was last pushed in August.

3/5 Depth expertise shipped Note Security Review before installing 2mo Maintenance Updated 2 mo ago 65K Adoption installs OK License MIT, commercial OK

What Web Quality Skills does

Web Quality Skills is an unofficial collection of six skills that make a coding agent treat web quality as something to measure first and fix second. The web-quality-audit skill runs an evidence-led review across categories, and ships a read-only bash script that scans HTML files for basics such as a missing doctype, viewport tag, lang attribute, title, image alt text and non-HTTPS URLs, and prints JSON. The performance and core-web-vitals skills explain how to separate field data (CrUX, real-user monitoring) from lab traces, then diagnose LCP, INP and CLS, with reference files for each metric. The accessibility skill follows WCAG 2.2 with a WCAG reference and a patterns file, the seo skill covers crawlability, metadata and structured data, and best-practices covers security headers and modern APIs.

When the agent has Chrome DevTools MCP, the skills tell it to run live Lighthouse audits and traces; without it they fall back to the Lighthouse CLI, axe or static source inspection. Each SKILL.md averages about 12.5 KB. The repo has a Claude Code plugin manifest and README instructions for Codex and Gemini CLI. It is stack-agnostic and has no tests or evals.

Good for

  • Front-end developers who want an agent to audit a page against Lighthouse and Core Web Vitals
  • Fixing accessibility and performance issues with before and after measurements
  • A quick checklist-style review of static HTML for SEO and best-practice basics

Not for

  • Backend or non-web projects
  • Deep SEO strategy work such as keyword research or link building

What's inside depth 3/5

Six skills averaging 12.5 KB, with nine reference files and one read-only audit script, but no tests or evals.

Skills
6
Reference docs
9
Scripts
1
Tests / evals
0
Templates
0
Avg SKILL.md
12.2 KB

Counted from the repository file tree. How we score depth.

Dependencies and costs

  • Optional: Chrome DevTools MCP for live Lighthouse audits and traces
  • Optional: Lighthouse CLI or axe as a fallback
  • jq for the audit script

Security review

Review before installing

Markdown audit guides for performance, Core Web Vitals, accessibility, SEO and best practices, with one local shell script that greps HTML files and prints JSON. The skills point the agent at Lighthouse and optionally the Chrome DevTools MCP for live audits, which are outside this repository. No allowed-tools, hooks or credential handling were found.

Worth knowing

  • Relies on a CLI or package we could not reviewThe audit workflow relies on Lighthouse CLI and optionally the Chrome DevTools MCP server, whose code is not in the repo (npx lighthouse appears unpinned in skills/accessibility/SKILL.md line 413).skills/web-quality-audit/SKILL.md:32

What we checked

The repository (31 files) on Oct 29, 2026. Not a full review: it relies on code outside the repository: Lighthouse CLI (run via npx in documentation examples); Chrome DevTools MCP server (optional, used for live audits and traces).

NVIDIA SkillSpector static scan: 13 pattern hits (MCP Rug Pull 7, Tool Misuse 2, Data Exfiltration 2, Agent Snooping 1, Prompt Injection 1). The 13 hits are unpinned npx mentions in docs, an analytics.example.com script tag used as a performance example, setup guides that mention agent config paths and rm of a skills folder, and an HTML comment ('With instructions') in an accessibility pattern file. None are actionable.

A review, not a certification. Skills change after we check them — read the files before installing.

License

MIT — commercial use allowed.

Can it run unattended?

Not really. These are audit and guidance skills driven by a user request; they have no loop, stop condition or persistent state, though the measure-fix-remeasure workflow is clear.

Alternatives to Web Quality Skills

Chrome DevTools MCP

ChromeDevTools/chrome-devtools-mcp

Google's Chrome DevTools MCP server and CLI, plus seven skills for debugging performance, memory leaks, cookies and accessibility in a live Chrome.

With caveats Check first Depth 3/5

squirrelscan Skills

squirrelscan/skills

Two skills and plugins for squirrelscan's website audit CLI: run 300+ SEO, security and accessibility rules, then fix the findings in code and re-audit.

With caveats Broad access Depth 4/5

Claude SEO

AgriciDaniel/claude-seo

A free Claude Code plugin with 26 SEO sub-skills and 19 agents for audits, schema, AI-search readiness and optional live-data extensions.

Recommended Check first Depth 4/5

Agent Skills (Addy Osmani)

addyosmani/agent-skills

25 engineering-lifecycle skills and 9 slash commands (spec, plan, build, test, review, ship) that make coding agents follow senior-engineer workflows.

Recommended Check first Depth 3/5

FAQ

What is Web Quality Skills?

It is an unofficial set of six agent skills by Addy Osmani that cover web performance, Core Web Vitals, accessibility, SEO, best practices and an overall web quality audit. They are based on Lighthouse and tell the agent to measure with field and lab data before changing code.

How do I install Web Quality Skills?

Run npx skills add addyosmani/web-quality-skills, or copy the skills folder into ~/.claude/skills. In Claude Code you can also add it as a plugin with /plugin marketplace add addyosmani/web-quality-skills; Codex and Gemini CLI have their own commands in the README.

Do I need Chrome DevTools MCP?

No. The skills prefer live Lighthouse audits and traces when Chrome DevTools MCP is available, but fall back to the Lighthouse CLI, axe or static source review.

Is Web Quality Skills safe?

We found no hidden network calls or credential access. The one script is a read-only HTML scanner, and the scanner's findings were documentation examples.

Sources: GitHub repository (stars, license, file tree, last push Aug 24, 2026); install counts from skills.sh via Best Skills (CC BY 4.0). Review based on the README and SKILL.md files as published.