Build a spec-compliant llms.txt file in two minutes. Fill in your site, add your most important pages, copy or download the result, everything runs in your browser, nothing is uploaded.
The spec reserves a section literally named Optional for secondary links, AI tools may skip it when context is tight. Name a section "Optional" and it inherits that meaning. Keep your 10–20 most important pages in normal sections.
Upload the file to your site root so it's reachable at yourdomain.com/llms.txt, served as plain text. Keep it updated, a map to 404s is worse than no map. Not sure whether you need one at all? Read our honest take: llms.txt, what it actually does.