Glossary
Agent card
A JSON document at /.well-known/agent-card.json describing what an agent can do, where to reach it and how to authenticate — A2A's discovery unit.
An agent card is how an A2A participant advertises itself: name, description, the skills it offers, the transport and URL to reach it, and the authentication it expects. An orchestrator fetches the card before sending anything, which makes discovery a plain HTTP GET rather than a directory lookup.
Because it is fetchable, it is checkable. Sato Hub probes the well-known path and records whether a card was served and parsed on a date — one of the few machine-checkable interface proofs the Sato Score credits.
A card describes intent, not capability. Anyone can serve one; serving it proves a document exists at a URL, not that the agent behind it does what the card says, or that it is running at all.
Where Sato Hub measures it
Numbers live on those pages and refresh on their own schedule; this definition does not restate them.
Related terms
Sources
Cite this page
Sato Hub. "Agent card (glossary)." Sato Hub, updated 2026-09-14, accessed 2026-09-14. https://satohub.ai/glossary/agent-cardData last refreshed 2026-09-14; this page is rebuilt daily. Citations carry the date so a reader can tell which snapshot a claim came from. Catalog data is licensed CC-BY-4.0.