# llms.txt & llms-full.txt: Teaching LLMs What Your Site Offers > Source: > Published: 2026-07-02 14:00:00+00:00 *Part of the Agent Readiness course — the web standards that decide whether an AI agent can actually read, understand, and act on your site. Measure any page against these with the Core Agent Vitals analyzer.* ## What it is `llms.txt` is a single markdown file you publish at your site root — `https://your-site.com/llms.txt` . It gives LLMs and AI agents a **curated, machine-readable map** of your site: your name, a one-line description, and the handful of links that actually matter (docs, pricing, API, key articles), each with a short note on what it contains. A companion file, `llms-full.txt` , goes further: it inlines the **actual content** of those key pages as clean markdown, so an agent can answer questions about your site from one fetch — no crawling, no HTML parsing, no JavaScript execution. Think of `llms.txt` as the table of contents and `llms-full.txt` as the printed book. The spec lives at [llmstxt.org](https://llmstxt.org). ## Why agents need it An AI agent works in a loop: **observe → reason → act**. The quality of everything downstream depends on that first observation. Without a machine-readable index, the agent's only option is to fetch your homepage HTML, strip the navigation and boilerplate, guess which links are relevant, fetch those, and repeat — spending tokens and time on markup it will throw away, and frequently landing on the wrong page. `llms.txt` collapses that whole discovery phase into one cheap, high-signal read: **Lower token cost.** A 200-line markdown index costs a fraction of rendering and tokenizing full HTML pages. On the analyzer this shows up directly in**Token Cost (TC)**.** Fewer wrong answers.**You decide what the agent sees first, so it stops inferring your structure from a cluttered DOM.** Deterministic entry points.**Agents that support the convention read`/llms.txt` before crawling — you get to curate the first impression. ## How to implement **1. Create /llms.txt** — an H1 with your name, a blockquote one-liner, then link sections: ``` > Developer documentation and API reference for the Acme platform. ## Docs - [Quickstart](https://acme.com/docs/quickstart): Install and make your first call in 5 minutes. - [Authentication](https://acme.com/docs/auth): API keys, OAuth, and scopes. ## API - [REST reference](https://acme.com/api): All endpoints, params, and response shapes. ## Optional - [Changelog](https://acme.com/changelog): Release notes. ``` **2. (Recommended) Create /llms-full.txt** — the same structure, but paste the clean markdown content of each key page inline. Generate it from your existing markdown/MDX at build time so it never drifts. **3. Serve both as text/plain at the root.** On a static host, drop the files in `public/` . On a framework, add two routes that return the files with `Content-Type: text/plain; charset=utf-8` .## Validate ``` curl -s https://your-site.com/llms.txt | head ``` You should get markdown, HTTP 200, and a `text/plain` content type. Then run your site through the [Core Agent Vitals analyzer](https://agentvitals.dev/analyze) — the **Agent Discoverability** panel checks for `llms.txt` at both `/llms.txt` and `/.well-known/llms.txt` , and flags it if the H1/blockquote structure is missing. ## Common mistakes **Publishing it as HTML.** If your framework wraps it in a layout, agents get a web page, not markdown. Serve raw`text/plain` .**Listing every URL.**`llms.txt` is a*curated*index, not a sitemap. If it lists 400 links it's noise — link the 5–15 pages that matter and let the sitemap handle the long tail.**No H1 or blockquote.** Parsers key off the`# Title` and`> one-liner` . Skip them and tools treat the file as malformed — it fails silently.**Letting** If you hand-maintain the inlined content, it drifts from the real pages within weeks. Generate it from source at build time or don't ship it.`llms-full.txt` rot.**Blocking the crawlers that would read it.** An`llms.txt` behind a`robots.txt` disallow, a login wall, or a bot-challenge is invisible. Keep the file and the pages it points to publicly reachable. *Next in the course: Sitemaps for Agent Discovery — the table of contents for everything llms.txt doesn't curate.*