AI Product Index / API catalog (RFC 9727)

API catalog (RFC 9727)

RFC 9727. If you already publish OpenAPI it states nothing new — it states it where a machine looking for APIs is specified to look.

How to pass it

Publish an RFC 9727 API catalog at /.well-known/api-catalog: a linkset pointing at your OpenAPI description and endpoints, served as application/linkset+json. It states nothing new if you already publish OpenAPI — it states it where a machine is specified to look.

Check your own site

Free, no signup, same endpoint that produced every grade on the leaderboard:

curl "https://index.percall.dev/api/score?url=https://your-site.example"

It returns the letter grade and every check by name with pass/fail. The $0.05 call at POST /api/audit adds why each one failed and a snippet with your origin already in it.

The rest of the checklist

6 more 2026 checks, and 13 from the other generation.

• llms.txt published 15 pts
• llms.txt has a title and summary 5 pts
• llms-full.txt published 5 pts
• robots.txt published 5 pts
• AI crawlers not blocked 10 pts
• sitemap.xml published 8 pts
• schema.org JSON-LD on the page 15 pts
• title and meta description 7 pts
• Open Graph tags 7 pts
• canonical URL declared 5 pts
• machine-readable alternates advertised 8 pts
• agent card at /.well-known/agent-card.json 10 pts
• served over HTTPS 5 pts
• Content Signals declared in robots.txt 3 pts
• A2A card at the 1.0 path 3 pts
• MCP server card published 2 pts
• Agent Skills index 2 pts
• Serves markdown to callers that ask for it 3 pts
• Web Bot Auth key directory 2 pts