Guide · Agent skill
How to use the Broken HTML Checker agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
The broken-html skill is a packaged checklist that teaches an AI agent to look for malformed HTML: unclosed tags, bad nesting, stray characters and missing head or body structure. This guide explains what agent skills are, how to install this one, how to ask for a review in plain language, and what to watch out for. By the end you will know how to run a structural HTML review on a template or rendered page and how to read the agent's findings.
Broken HTML Checkerthedaviddias/Front-End-Checklist · MIT Download the skill Quick start
- 1Download the ZIP. Get the broken-html skill ZIP from the page where you found this guide.
- 2Unzip into a skills folder. Extract it into ~/.claude/skills/ for personal use, or .claude/skills/ inside your project.
- 3Or upload in the Claude apps. In the Claude apps, open Settings, go to Capabilities, then Skills, and upload the ZIP.
- 4Provide the page or template. Paste the template source or the rendered HTML you want reviewed.
- 5Ask in plain language. Request a check of HTML structure, crawlability or indexability for that page.
- 6Review and verify the fixes. Read the flagged routes or templates, apply the corrections and confirm the rendered output.
What does the broken-html skill make the agent do?
When you ask for it, the agent reviews your templates or rendered pages against a set of HTML structure rules. It looks for tags that are not closed, elements nested incorrectly, stray tags or unescaped characters in the source, and a document structure that lacks valid head and body sections.
The skill also explains why these problems matter. The source notes that malformed HTML can cause rendering differences across browsers and may stop search engine crawlers from parsing and indexing content accurately. The agent proposes corrections that close tags and nest elements according to the HTML5 specification.
The skill tells the agent to verify the final rendered HTML and the HTTP response, not only the source files, because templates can produce different output once they run.
How do you install the broken-html skill?
The skill is distributed as a ZIP file from the page where you found it. Download the ZIP, then unzip it into one of two locations: ~/.claude/skills/ for your personal use, or .claude/skills/ inside a project if you want the skill to apply to that project only.
Alternatively, you can upload the skill in the Claude apps. Open Settings, go to Capabilities, then Skills, and upload the ZIP there.
- Personal install: unzip into ~/.claude/skills/
- Project install: unzip into .claude/skills/ in your project folder
- Claude apps: Settings → Capabilities → Skills, then upload the ZIP
How do you trigger the skill with a natural request?
You do not need a special command. The skill's description tells the agent when to use it, so ask in plain language about HTML structure, crawlability or indexability. Paste a template or point the agent at a page, and say what you want checked.
Good requests name the page and the concern. Mention the audience if it matters, for example a developer preparing a release or someone investigating why a page is not indexed.
- Check this product template for unclosed or badly nested tags before release.
- Why might Google not be indexing this page? Check the HTML structure.
- Audit the head and body structure of the rendered homepage.
- Review this layout file for stray characters that could break parsing.
What does the agent need to do a good review?
The skill itself lists no requirements, and it does not run scripts or use the network. The quality of the review depends on what the agent can see. Give it the template source, or the rendered page output, so it can check the final HTML.
If the agent cannot see the rendered output and has no page or fetched content, it can only reason about source files. The skill is designed to check rendered HTML and the HTTP response, so supply those when you can.
- Template or source files for the page
- The rendered HTML, if you can provide it
- The HTTP response details, if relevant
What should you check in the agent's output?
Treat the findings as a guided checklist, not a complete audit. The skill can miss issues that a dedicated HTML validator or crawler would catch. It also does not cover security or accessibility compliance sign-off, since it only addresses structural HTML errors.
Ask the agent to name the exact routes or templates where problems appear and to explain how to verify the final output. Then confirm each fix by checking the rendered page yourself.
- Confirm that flagged tags are really unclosed in the rendered output
- Run a dedicated validator if you need full coverage
- Do not treat a clean result as a compliance sign-off
What people use it for
- Reviewing SEO-facing templates for unclosed or badly nested tags before a release
- Investigating why a page may not be indexed or parsed correctly by search engines
- Auditing a site for basic HTML validity across templates
- Explaining to a non-specialist why a structural HTML error could affect crawling or accessibility
Frequently asked questions
How do I install the broken-html agent skill?
Download the ZIP from the page where you found the skill and unzip it into ~/.claude/skills/ for personal use or .claude/skills/ in a project. You can also upload the ZIP in the Claude apps under Settings, then Capabilities, then Skills.
Does the broken-html skill require anything to run?
The skill lists no requirements. It does not run scripts and does not use the network, so it works by reasoning over the HTML you provide.
Is the broken-html skill free?
The skill is licensed under MIT, as stated on its listing. This guide does not state pricing beyond that licence.
Can the skill replace an HTML validator?
No. The skill is a guided checklist and may miss issues that a dedicated HTML validator or crawler would catch. Use a full validator when you need complete coverage.
Why does the agent need the rendered HTML and not just my source files?
The skill tells the agent to verify the final rendered HTML and HTTP response, because templates can produce different output than the source suggests. Without the page or a fetch, the agent can only reason about source files.
What is the difference between this skill and a broader SEO audit?
This skill focuses on structural HTML errors such as unclosed tags, bad nesting and missing head or body structure. It does not cover security or accessibility compliance sign-off, so it is narrower than a full audit.
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Our verdict
This skill suits developers who want a second review of SEO-facing templates before release, and SEO or marketing staff checking whether a page is parsed correctly. It is a focused checklist, not a replacement for a full HTML validator, crawler, or security and accessibility sign-off, so choose a dedicated tool when you need complete coverage.
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