# Lighthouse's agentic browsing audit: what it checks and how to pass

> What the Agentic Browsing category in recent Lighthouse versions checks, how to run it, what each audit means, and the fixes that moved our own scores.

Canonical page: https://aispeedforce.com/blog/lighthouse-agentic-browsing-audit/

Last updated: 2026-09-23

Recent Lighthouse versions add an Agentic Browsing category that checks how well AI agents can read and use a page. Here is what it looks at and how to fix what it finds.

[SEO](https://aispeedforce.com/blog/category/seo/) Published 23 September 2026 5 min read By AI SpeedForce

Recent Lighthouse versions include an Agentic Browsing category that checks how well AI agents can read and use a page. It looks at the accessibility tree, WebMCP tools registered by the page, whether the site publishes an llms.txt file, layout stability, and the ai-catalog manifest if one exists. You run it like any other Lighthouse audit, and most of its failures are fixed once in a shared template.

Lighthouse has long measured performance, accessibility, best practices and SEO for people. This category asks a newer question: if an agent opens this page to do something for a user, can it understand what is there and act on it reliably?

## What the category checks

| Area | What it checks |
|---|---|
| Accessibility tree | Elements have names, roles and a sensible structure |
| WebMCP | Tools registered in the page, and whether their schemas are valid |
| llms.txt | The site publishes a readable llms.txt |
| Layout stability | The page does not shift while an agent reads it |
| ai-catalog | The manifest, if present, matches its schema |

What the category looks at

- **The accessibility tree.** Agents that operate a browser often read the same structure screen readers do: roles, names and states. Buttons without names, unlabeled fields and duplicate landmarks all make a page harder to operate. See [how AI agents read web pages](https://aispeedforce.com/blog/how-ai-agents-read-web-pages/).
- **WebMCP.** Audits report the tools a page registers through the browser's model context API and check that their input schemas are valid. Our [WebMCP guide](https://aispeedforce.com/blog/webmcp-explained/) explains the API.
- **llms.txt.** Whether the site publishes a readable [llms.txt](https://aispeedforce.com/blog/llms-txt-explained/) file.
- **Layout shift.** An agent that reads a page, then clicks where a button was a moment ago, fails the same way a person does. Cumulative Layout Shift is counted here too.
- **The ai-catalog schema.** If the site publishes `/.well-known/ai-catalog.json`, it is validated against the draft specification. See [agent skills and the ai-catalog](https://aispeedforce.com/blog/agent-skills-and-ai-catalog/).

The exact list of audits can change between releases. Treat the categories above as the current shape and check the report your version produces.

## How to run it

The simplest route is the command line, which always gives you a current version:

`npx lighthouse https://example.com/ --output=html --output-path=report.html`

The report lists every category the installed version supports. To see which categories and audits your version has, run `npx lighthouse --list-all-audits`. Lighthouse in Chrome DevTools may lag behind the command-line release, so if the category is missing there, use the command line. Documentation for Lighthouse itself is on [developer.chrome.com](https://developer.chrome.com/docs/lighthouse/overview).

Audit on mobile settings, which is the default, and on more than the home page. Include a content page, a page with a form, and anything with a checkout.

## Fix templates, not pages

A practical audit loop

When we audited this site, every issue in the SEO and agentic categories came from a shared file: the robots.txt, the header markup, or the ai-catalog generator. Fixing each once moved every page at the same time. That pattern is common, because most pages on a site share their chrome and head.

The fixes that moved our scores, all of them general:

- **robots.txt validity.** A non-standard directive we had added made Lighthouse mark the whole file invalid, which cost SEO points on every page. Removing it fixed it. Keep robots.txt to standard directives; see [robots.txt for AI crawlers](https://aispeedforce.com/blog/robots-txt-for-ai-crawlers/).
- **ai-catalog schema.** Our manifest had host fields and entry types the schema does not allow. We kept the host block to its allowed fields and listed only agent skills, with the standard skills media type.
- **Duplicate landmark names.** The header menu and the mobile menu were both named "Primary". Giving the mobile menu its own name cleared it.
- **Decorative icons.** An icon inside a button that already had a text label was exposed to the accessibility tree. Marking it `aria-hidden` fixed it.
- **Endless animations.** Decorative diagram animations that looped forever used a property the browser cannot hand off to the graphics layer, which blocked the main thread on mobile. Running them a few times and stopping fixed the performance score as well.

Fixes that moved our scores

## Read the accessibility tree yourself

The audit tells you whether the tree is sound. To see what an agent sees, open Chrome DevTools, go to the Elements panel and switch on the accessibility tree view. Walk through your header, main content and forms. Every control should have a name that says what it does, every image should either have useful alternative text or be hidden as decorative, and the landmarks (header, navigation, main, footer) should each appear once with a distinct name. If a button reads as "button" with no name, an agent has no idea what it does.

## Where performance comes in

Agents load pages in real browsers, often on limited resources, and they wait for the page to settle before acting. A page that keeps the main thread busy or keeps shifting slows every task an agent runs on it. That is why layout stability sits inside this category, and why fixing long main-thread work helps agents as well as people. Oversized images in the header, endless animations and render-blocking scripts are the usual causes, and each is fixed once in a template.

## What Lighthouse does not check

Lighthouse audits one page at a time. Several agent-readiness signals live at the site level: Content Signals in robots.txt, the [API catalog and Link headers](https://aispeedforce.com/blog/api-catalog-and-link-headers/), [Markdown on request](https://aispeedforce.com/blog/markdown-for-agents-content-negotiation/), and the agent skills index. Our free [agent-readiness scan](https://aispeedforce.com/agent-ready/) checks those across the whole site and explains each gap, so the two tools together cover both levels.

Keep the reports from each run. Comparing them after a release shows quickly whether a template change helped or quietly broke something for agents.

## Next step

Run Lighthouse on three representative pages, group the failures by the file that causes them, and fix the shared ones first. Then run the [agent-readiness scan](https://aispeedforce.com/agent-ready/) for the site-wide checks. If you want the fixes done for you, our [SEO work](https://aispeedforce.com/services/seo/) covers them.

## Questions about this topic

### Which Lighthouse version has the Agentic Browsing category?

It appears in recent Lighthouse releases. If your copy does not list it, update Lighthouse or run the latest version from the command line, and check the list of categories it reports.

### Does the agentic browsing score affect search rankings?

Not directly. It measures how usable a page is for AI agents. Several of its checks overlap with accessibility and performance, which matter for people too.

### Do I need WebMCP to score well?

No. The WebMCP audits report tools if a page registers them and check that their schemas are valid. A page without tools is not penalized for that alone.

## Related posts

- [What is agentic browsing? A plain guide for site owners](https://aispeedforce.com/blog/what-is-agentic-browsing/): Agentic browsing 23 September 2026. AI agents now open web pages, read them and take actions for the people who send them. Here is what agentic browsing is, how it differs from a person browsing, and the changes that help a site work well for both.
- [llms.txt explained: what it is and how to write one](https://aispeedforce.com/blog/llms-txt-explained/): SEO 23 September 2026. llms.txt is a short Markdown file at your site root that tells language models what your site is and where the important pages are. It is a proposal, not a standard, and it is cheap to publish.
- [robots.txt for AI crawlers: GPTBot, ClaudeBot and the rest](https://aispeedforce.com/blog/robots-txt-for-ai-crawlers/): SEO 23 September 2026. AI providers run separate crawlers for training, for search and for fetching a page a user asked about. robots.txt lets you treat each one differently. Here is who is who and how to write the rules.
- [All posts](https://aispeedforce.com/blog/)
- [More on SEO](https://aispeedforce.com/blog/category/seo/)
- [Agent-readiness scan](https://aispeedforce.com/agent-ready/)

## See how your own site scores

The free agent-readiness scan checks the files, headers and endpoints this blog writes about, and tells you what to fix first.