AI Product Index / robots.txt published
Its absence is ambiguous rather than permissive, and several crawlers resolve ambiguity as "stay out". This is the cheapest check on the list to pass.
Publish /robots.txt — its absence is ambiguous, and some crawlers treat ambiguity as disallow.
# /robots.txt
User-agent: *
Allow: /
Sitemap: {{ORIGIN}}/sitemap.xml
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.