AI Product Index / A2A card at the 1.0 path
A2A reached 1.0 and the card moved to /.well-known/agent-card.json. A spec-compliant client never looks at the old path, so a site serving only the old one is invisible to exactly the clients that implemented the spec properly.
A2A 1.0 reads /.well-known/agent-card.json; /.well-known/agent.json is the pre-0.3 path a 1.0 client never looks at. Serve the same document at both while the installed base catches up.
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.