# Lighthouse adds an llms.txt check to its agentic browsing audits

> Lighthouse 13.2.0 added an experimental llms.txt audit, on by default from 13.3.0. Exactly what it checks, and why it is not a Google Search ranking signal.

Source: https://llmstextgenerator.com/llms-txt-news/lighthouse-llms-txt-audit/
Last updated: 17 October 2026

Google’s Lighthouse tool now checks llms.txt in an experimental “agentic browsing” category. It looks for an H1, a link and some content, nothing more.

Happened on 1 May 2026

## What happened?

Lighthouse 13.2.0, released on 1 May 2026, added an “agentic browsing” category with an llms.txt check (its release notes: “config: implement llms.txt check for AI agents”). Lighthouse 13.3.0, on 7 May, made the category part of the default run. Chrome’s documentation calls it “experimental and based on proposed standards”, and testing it needs Chrome 150 or later.

## What does the audit check?

The audit is titled “llms.txt follows recommendations”. From its source code:

| Result | When |
| --- | --- |
| Fails | The request errors, or the server answers with a 5xx or 429 |
| Not applicable | Any other 4xx, such as a 404 for a site without a file |
| Fails: “File is missing a required H1 header” | No `# Title` line |
| Fails: “File does not appear to contain any links.” | No Markdown link |
| Fails: “File is suspiciously short.” | Fewer than 50 characters |

A Chrome blog post in June described the category as “informational and unbenchmarked”. Lighthouse 13.5.0, in September, grouped the llms.txt check with other agent discovery audits.

## What does it mean for your site?

**This is a quality check in a developer tool, not a sign that Google Search uses the file.** Google’s Search guidance still says Search ignores llms.txt.

Not having a file costs you nothing here: a 404 is “not applicable”. If you do publish one, it should pass, and a broken file that returns a server error fails. The [validator](https://llmstextgenerator.com/llms-txt-validator/) checks the same basics plus links, descriptions and how the file is served.

## Sources

**Source:** [Lighthouse 13.3.0 release notes](https://github.com/GoogleChrome/lighthouse/releases/tag/v13.3.0), [Chrome for Developers: the llms.txt audit](https://developer.chrome.com/docs/lighthouse/agentic-browsing/llms-txt), [The audit’s source code](https://github.com/GoogleChrome/lighthouse/blob/main/core/audits/agentic/llms-txt.js)

**Coverage:** [Search Engine Journal, 20 May 2026](https://www.searchenginejournal.com/googles-llms-txt-guidance-depends-on-which-product-you-ask/575431/)

[All llms.txt news](https://llmstextgenerator.com/llms-txt-news/)