# Lighthouse and llms.txt: what the audit checks

> What the llms.txt audit in Lighthouse and PageSpeed Insights checks, when it appeared, what it does not prove, and whether to create the file for the sake of the report

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

Since May 2026 Lighthouse, the site auditing tool from the Chrome team, looks at whether a site has `llms.txt`. The audit belongs to the experimental Agentic Browsing category.

It establishes one fact: whether `/llms.txt` answers. Lighthouse does not judge what the file contains.

It does not mean Google Search uses the file. The Search documentation says the opposite.

experimental category · Chrome documentation
## How the audit arrived

- History of the llms.txt audit in Lighthouse
- Lighthouse 13.2.0
- The llms.txt audit lands in the code.
- Lighthouse 13.3.0
- The audit is on by default in the Agentic Browsing category.
- The agent-ready toolkit
- Chrome describes how to prepare a site for agents.
- Lighthouse 13.4.1
- The audit becomes available through the PageSpeed Insights API.
- Lighthouse 13.5.0
- Agent discovery audits are gathered into one group.

How it unfolded: [the check turned on by default](https://llms-full-txt.ru/en/blog/lighthouse-checks-llms-txt/), [discovery checks grouped](https://llms-full-txt.ru/en/blog/lighthouse-13-5-agent-discovery/).

## What exactly is checked

| The site's answer at `/llms.txt` | What Lighthouse reports |
|---|---|
| The file is served | the audit passes |
| `404` | "not applicable": a missing file is not an error |
| A server error | a warning |

Three things worth knowing:

- **Content is not judged.** An empty file and a careful map are equal to the audit.
- **The category has no overall score.** There is no familiar 0 to 100 number for Agentic Browsing.
- **The category is experimental** and needs a recent Chrome. Its set of audits changes between releases.

Hence a trap: when a site answers any unknown address with a `200` page, the audit may pass without a file. How to make sure the file is real: [Validating files and markup](https://llms-full-txt.ru/en/guides/validation/).

## Chrome and Search talk about different things

- Two Google products
- Chrome, Lighthouse
- preparing a site for agents
- Checks that llms.txt exists
- Speaks about agents working in a browser
- Does not claim that Google products read the file
- Google Search
- index and ranking
- Does not use llms.txt
- The file neither helps nor harms rankings
- Ordinary SEO applies to AI features of Search
- There is no contradiction
- Lighthouse checks how convenient a site is for agents. The Search documentation describes how results are built. These are different tasks.

## Should you create the file for the report

**Confirmed**

- Lighthouse checks whether `/llms.txt` answers.
- A missing file does not lower the familiar performance, accessibility and SEO scores.
- The audit is described in the [Chrome documentation](https://developer.chrome.com/docs/lighthouse/agentic-browsing/llms-txt).

**Not proven**

- That passing the audit affects rankings or appearance in AI answers.
- That the category will stay as it is: it is experimental.

**What it does not mean**

- It is not a confirmation that the file is well made.
- It is not a signal for Google Search.

Create the file when the site has material an agent benefits from finding fast: documentation, a catalog, a knowledge base. The Lighthouse audit will then pass as a side effect.

Creating an empty file to clear a line from the report is pointless: that is how files without a single link appear.

## What to read next

- [Status of the standard](https://llms-full-txt.ru/en/guides/standard-status/) - who supports the format and on what terms
- [Does llms.txt work](https://llms-full-txt.ru/en/guides/does-llms-txt-work/) - what the studies show
- [An AI-ready site](https://llms-full-txt.ru/en/guides/ai-ready-site/) - every layer in order