# Lighthouse starts checking llms.txt

> In Lighthouse 13.3.0 the llms.txt check is on by default - what exactly it looks at, why an empty file passes and what it does not prove

Page: https://llms-full-txt.ru/en/blog/lighthouse-checks-llms-txt/
Site index: https://llms-full-txt.ru/en/llms.txt

Event date: 2026-05-07

Published: 2026-10-03

[Lighthouse 13.3.0](https://github.com/GoogleChrome/lighthouse/releases/tag/v13.3.0) came out on May 7, 2026. In it the `llms.txt` check is on by default in the experimental Agentic Browsing category. A week earlier, in version 13.2.0, the check appeared in the code.

Lighthouse is the Chrome team's tool for checking page speed, accessibility and SEO. Its report now has a line about a file for agents.

## What is checked

One fact: whether `/llms.txt` answers.

| Site response | What the report shows |
|---|---|
| The file is served | the check passes |
| Status `404` | "not applicable" |
| Server error | a warning |

Lighthouse does not read the content of the file. An empty file and a thought-out map are equal for the check.

## Why it is a notable event

Before May 2026 no mainstream tool for site owners mentioned `llms.txt`. Now everyone who opens a Lighthouse report learns about the file.

## What the check does not mean

- It is not a signal for Google Search. A month later [Google wrote](https://developers.google.com/search/docs/fundamentals/ai-optimization-guide) in its documentation that Search does not use such files.
- A missing file does not lower the performance, accessibility or SEO scores.
- The category is experimental and has no overall score.

## What a site owner should do

Creating an empty file for the sake of a line in a report is not worth it: that is how files without a single link appear. If the site has documentation, a catalog or a knowledge base, make a real file and the check will pass by itself. The detailed breakdown: [Lighthouse and llms.txt](https://llms-full-txt.ru/en/guides/lighthouse/).