What is a llms.txt file and do you need one?

What is llms.txt?

In a nutshell: llms.txt is a small text file that gives AI tools a tidy, curated map of your website. It’s fairly quick to create and is becoming part of how sites get ready for AI search. It works best as one piece of a wider AI visibility setup rather than a fix on its own.

The problem it tries to solve is a real one, websites are messy for AI models to read, as there are menus, cookie banners, scripts, pop-ups and far more text than a model wants to wade through to answer one question. llms.txt cuts through that with a plain Markdown file at yoursite.co.uk/llms.txt: a short summary of who you are, plus links to the pages that matter.

Think of it as the cheat sheet you’d hand a new starter on their first morning, rather than giving them the keys to the filing cabinet and wishing them luck.

It’s a community proposal rather than an official web standard like robots.txt. There’s also a companion file, llms-full.txt, which puts the full text of your key pages in one place instead of just linking to them.

What does one look like?

Here’s an example for a made-up Wakefield joinery firm:

# Bramley & Sons Joinery

> Family-run bespoke joinery firm in Wakefield, West Yorkshire. Kitchens, staircases and fitted furniture for homes across Yorkshire since 1998.

## Services
- [Bespoke kitchens](https://example.co.uk/kitchens/): Handmade kitchens, from design to fitting
- [Staircases](https://example.co.uk/staircases/): Oak and painted staircases, new and replacement

## About
- [Our story](https://example.co.uk/about/): Who we are and how we work
- [Contact](https://example.co.uk/contact/): Quotes, opening hours and showroom address

## Optional
- [Journal](https://example.co.uk/journal/): Project write-ups and advice

A single heading with your business name, concise summary, then sections of links, each with a short note on what’s there. The Optional section tells an AI tool it can skip those links if it’s short on space.

Reasons to have one

It’s part of a bigger picture. On its own it’s a small step, but alongside the other work below, it helps make your site properly readable for AI tools.

Lighthouse now checks for it. In May 2026, Google’s Lighthouse tool (the one behind PageSpeed scores) gained a new Agentic Browsing category. It looks at how easily AI agents can use your site, and one of its checks is llms.txt; does it have a heading, is it long enough to be useful, does it contain links. It’s a small signal, but it shows where things are heading.

It makes you get your house in order. Writing a good llms.txt means deciding which pages matter most and describing each in one clear line. Plenty of businesses have never done that, and it often shows up pages that are missing, out of date or saying the wrong thing.

What else gets you seen by AI

llms.txt works best as part of a wider setup, and these are the other areas we look at when we’re optimising a site for AI search:

• Let the crawlers in. Check your robots.txt, firewall and any Cloudflare bot settings aren’t quietly blocking GPTBot, ClaudeBot or PerplexityBot.
• Answer questions plainly. Pages that give a clear answer near the top, in normal language, are far easier for AI tools to quote than pages full of fluff.
• Get mentioned in the right places. AI tools lean heavily on what other sites say about you: reviews, directories, press and industry roundups.
• Build clean, accessible pages. Proper headings, structured data and tidy HTML help screen readers, search engines and AI agents all at once. It’s also most of what that Lighthouse category actually checks.

How to add one to a WordPress site

• Write it, keeping the summary factual and concise
• Check your SEO plugin first as some can generate one for you
• Upload it to the root of your site
• Clear your cache
• Run Lighthouse, tick the Agentic Browsing option in Chrome DevTools to make sure the file passes.
• Keep it updated with new services

The verdict

llms.txt is a sensible, fairly quick step that’s worth taking now while the standard settles. On its own it won’t transform your AI visibility, but as part of a proper setup it helps make sure AI tools can find, read and understand your business.

If you’d rather not fiddle with it yourself, it’s something we set up as part of our AI search optimisation work, alongside the bits that move the needle most.