Why it matters
llms.txt is a curated Markdown index for inference-time agents, used mostly by coding agents. Adoption is cheap but evidence of answer-engine use is thin (97% of files got zero requests in Ahrefs' 2026 study), so this is informational.
How to fix it
Add app/llms.txt/route.ts with an H1, a > summary and sections of links to Markdown pages.
Example
// app/llms.txt/route.ts
export const dynamic = 'force-static'
export function GET() {
const body = [
'# Acme',
'',
'> Acme builds fast widgets for teams. Open source, MIT licensed.',
'',
'## Docs',
'',
'- [Quick start](https://acme.example/docs/quick-start.md): install and render a widget in 2 minutes',
'',
'## Optional',
'',
'- [Changelog](https://acme.example/changelog.md)',
].join('\n')
return new Response(body, { headers: { 'Content-Type': 'text/markdown; charset=utf-8' } })
}References
More ai search rules
void geo reports 41 rules in this category. Generative-engine optimisation: whether AI crawlers that don't run JavaScript see the same content, valid and visible JSON-LD, an explicit AI robots policy, llms.txt, Markdown mirrors and answer-first writing.
markdown-alternateNo working Markdown alternate for this content pagemarkdown-mirror-indexableMarkdown mirror can compete with the HTML page, or diverges from itmarkdown-negotiation-varyAccept: text/markdown negotiation without Vary: Acceptmarkdown-negotiationNo Markdown response for Accept: text/markdownllms-txt-error/llms.txt returns a server errorllms-txt-invalid/llms.txt doesn't follow the llms.txt formatllms-txt-broken-links/llms.txt links to URLs that failllms-txt-not-linkedllms.txt exists but isn't linked from the home page