Whether a domain is in CrawlCheck's registry and what it serves: llms.txt, agents.md, a media kit at /.well-known/media-kit.json, a reciprocity-tested entity graph, an AI access policy that names crawlers, and agent-callable surfaces. With no domain, returns the shelf counts across every measured site. A row exists because a fetch produced it; nothing here is self-reported and no payment moves a shelf.