llms-txt-aware

llms-txt-aware is a skill for Claude Code from MauricioPerera/llms-txt-skills. It costs 127 tokens per session (2,204 once invoked), scanned A, original, MIT.

A workflow rule for websites that requires checking a domain's /llms.txt file before fetching or scraping it. That file is a site-provided guide for AI tools, including available endpoints and usage notes.

In plain words
What is it for?
Finding and reading /llms.txt before web requests, API calls, HTML scraping, or constructing URLs for a domain. It does not apply to generic web searches or already documented local sites.
Why use it?
It reduces guesswork when an agent interacts with an unfamiliar website or public API. The agent can use the site's own operating instructions before making requests.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the llms-txt-aware plugin — 1 skill shipped together

Good fit Finding and reading /llms.txt before web requests, API calls, HTML scraping, or constructing URLs for a domain. It does not apply to generic web searches or already documented local sites.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mauricioperera/llms-txt-skills/llms-txt-aware
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add MauricioPerera/llms-txt-skills --skill llms-txt-aware
Clone the repo
git clone --depth 1 https://github.com/MauricioPerera/llms-txt-skills

Made for: Claude Code.

Or install llms-txt-aware, the plugin that ships this one along with the rest of its 1 skill.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for llms-txt-aware

README.md
[![agentmods](https://agentmods.dev/badge/skills/mauricioperera/llms-txt-skills/llms-txt-aware/github.svg)](https://agentmods.dev/skills/mauricioperera/llms-txt-skills/llms-txt-aware)
Your own site
<a href="https://agentmods.dev/skills/mauricioperera/llms-txt-skills/llms-txt-aware"><img src="https://agentmods.dev/badge/skills/mauricioperera/llms-txt-skills/llms-txt-aware/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for llms-txt-aware

Your own site · 80×15
<a href="https://agentmods.dev/skills/mauricioperera/llms-txt-skills/llms-txt-aware"><img src="https://agentmods.dev/badge/skills/mauricioperera/llms-txt-skills/llms-txt-aware.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 127 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,204 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00127 $0.02204
Opus 5.5 $0.00051 $0.00882
Sonnet 5.5 $0.00025 $0.00441
Haiku 4.5 $0.00013 $0.00220

Measured 2mo ago against content hash 6f0604e555d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

llms-txt-aware scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/llms-txt-aware/skills/llms-txt-aware/SKILL.md · 161 lines

How it starts

The opening of the file, as written. The whole thing — 161 lines — stays where its author put it; the contents beside it link to each section on GitHub.

llms-txt-aware

Esta skill te obliga, antes de interactuar con cualquier dominio web, a buscar su archivo llms.txt y usarlo como fuente de verdad. El archivo entero es contexto operativo, no solo la sección ## Skills.

Cuándo activar

Activá esta skill cada vez que vayas a:

  • Hacer un web_fetch o request HTTP a un dominio que todavía no chequeaste en esta conversación.
  • Llamar una API REST/GraphQL pública sin documentación local previa.
  • Scrapear contenido HTML de un sitio.
  • Construir una URL del sitio (paths, endpoints, querystrings, headers).
  • Inferir el comportamiento esperado de un servicio remoto.

No la actives para:

  • Búsquedas web genéricas (web_search).
  • Dominios que ya chequeaste y cacheaste en este mismo turno.
  • Recursos binarios directos (imágenes, PDFs, descargas).
  • Sitios que ya tenés documentados localmente (docs en el repo del usuario, OpenAPI a mano, etc).

Procedimiento

Paso 1: extraer el origen

Dado una URL objetivo como https://demo.ejemplo.com/api/x/y?z=1, el origen es https://demo.ejemplo.com. Trabajá siempre a nivel de origen, no de path.

Paso 2: probar el /llms.txt

Hacé GET {origen}/llms.txt con timeout corto (5 a 10 segundos).

Estados posibles y qué hacer con cada uno:

  • 200 OK con Content-Type: text/markdown, text/plain o body que empieza con # : seguir al paso 3.
  • 200 OK pero el body es HTML (la SPA devuelve el index): tratarlo como 404, no existe llms.txt real.
  • 404, 403, 5xx, timeout, o redirect que termina en HTML: cachear "no llms.txt" para este origen y seguir tu flujo normal.

Fallback opcional: si el principal devuelve 404, probá una sola vez {origen}/.well-known/llms.txt. Si tampoco está, cortás ahí.

Paso 3: leer el archivo COMPLETO

Esto es lo crítico. NO te limites a la sección ## Skills. El archivo entero es manual del sitio. Tenés que extraer y usar:

  • # Título y > tagline: identidad y propósito del sitio.
  • Secciones de endpoints, paths, métodos HTTP, headers requeridos.
  • Parámetros con sus tipos, si son obligatorios u opcionales, defaults y límites.
  • Respuestas esperadas: códigos HTTP, content-types, forma del payload.
  • Cache, rate limits, política de retry.
  • Ejemplos canónicos de URLs y bodies.
  • Constraints explícitos: paths que NO existen, endpoints que NO hay que llamar.
  • Notas para agentes (suelen aparecer como ## Notes for agents, ## For LLMs, ## Agent guidance).
  • Sección ## Skills si está, para descubrir skills publicadas (ver paso 5).

Read the full file on GitHub · 161 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2mo ago First seen · 161 lines · 127 tokens per session scan A 6f0604e555d8

Subscribe to this mod's changes

llms-txt-aware is a skill published in the GitHub repository MauricioPerera/llms-txt-skills (2 stars, last pushed 2mo ago), licensed MIT. It adds 127 tokens to every session and 2,204 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

llms-txt-aware compared with skills from other repositories

llms-txt-aware next to 6 skills from other repositories
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llms-txt-awareMauricioPerera/llms-txt-skillsSkill22mo agoMITA127Claude Code
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skill-bodycitrolabs/ego-liteSkill22ktodayMITA0Claude Code, Codex
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