Should you add an llms.txt file? What 34 measured websites actually do

llms.txt is the file GEO consultancies most like to sell: "an introduction to your business, written for AI." Before you pay for one, here is what we found when we scanned 34 head-of-market websites for ten AI-facing files — the full data is on the benchmark page.

Who actually has one

Across the 34 brands: 22 of 34 serve an /llms.txt; 12 also serve the longer llms-full.txt. Adoption splits sharply by industry — 13 of 16 software companies have one, versus 4 of 8 DTC brands and 5 of 10 China-based brands. Companies whose customers are developers publish developer files. That is a less exciting explanation than "the leaders are ahead of you," and it fits the data better.

The uncomfortable finding: most of them were written by Shopify

Nine of the 34 serve an agents.md — the file that tells an AI agent who you are and where to transact. We read all nine. Six of them are the same file: a 4,100–4,300 byte template headed "Agent Instructions — {brand}", generated by Shopify, pointing an AI shopping agent at shop.app (Shopify's own checkout) eight times per file. Compared character by character, two brands' copies differ only in the brand name and one policy link.

So the "AI introduction" most DTC brands shipped is a template their platform wrote, selling checkout infrastructure that is not theirs. If you have a store on a platform, check /agents.md and /llms.txt on your own domain before assuming they introduce you.

What llms.txt does, and what it does not

What it does: give an AI system that is already reading your domain a tidy, self-authored summary — what you sell, for whom, key pages. It is hygiene. Ours is generated from the same code as our reports, so it cannot drift.

What it does not do: make an assistant recommend you. Google's own documentation says it does not read llms.txt, and nothing in our benchmark sample suggests the file separates the visible from the invisible. A one-person business with no llms.txt can be named in every answer; a household name with three AI files can be described wrong. The things that move visibility are measured elsewhere — being named when buyers ask, and being present in the sources the answers are built from.

The verdict

Write one — in an afternoon, yourself. Structure: what the business is, in plain sentences; what you sell and roughly what it costs; the pages that matter; how to contact a human. Keep it honest and current. Do not buy it as a package, and do not expect it to do anything on its own.

Then check whether any of it worked: the free check reads your AI-facing files as part of the pre-flight, and a full AI visibility audit tells you whether the assistants that matter are actually using any of it.