# Agent Card

> A JSON document an A2A agent publishes at /.well-known/agent-card.json that advertises its identity, skills, endpoints and authentication.

_The Agentic Web Lexicon · /glossary/agent-card · [JSON](/api/glossary/agent-card) · [all The Agentic Web Lexicon](/glossary)_

- **term:** Agent Card
- **category:** identity
- **short_def:** A JSON document an A2A agent publishes at /.well-known/agent-card.json that advertises its identity, skills, endpoints and authentication.
- **long_def:** The Agent Card is A2A's discovery primitive — a machine-readable 'business card' hosted at a well-known URI (per RFC 8615) listing the agent's name, description, version, service endpoints, supported interfaces, capabilities (e.g. streaming) and the AgentSkill objects it offers. A client reads the card to decide whether and how to delegate a task to the agent.
- **see_also:** a2a, agent-identity, agntcy
- **etymology_origin:** Defined by the Agent2Agent (A2A) protocol; served at the well-known URI /.well-known/agent-card.json following RFC 8615 'Well-Known Uniform Resource Identifiers'.
- **related_to:** a2a, agent-identity, agntcy, web-bot-auth
- **contrast_with:** Unlike llms.txt or AGENTS.md, which describe a site or repository for ingestion, an Agent Card describes a callable AGENT — its skills, endpoints and auth — so other agents can discover and delegate work to it.
- **example:** An A2A agent publishes its Agent Card at /.well-known/agent-card.json, listing skills and endpoints so client agents can discover and delegate to it.
- **source:** https://a2a-protocol.org/dev/topics/agent-discovery/
- **status:** active
- **why_it_matters:** The Agent Card is how a service makes itself discoverable and delegable in a multi-agent system; publishing one is the A2A counterpart of having a sitemap for agents.
- **sameAs:** —
- **bridge_entity:** protocols/interop/a2a
- **last_verified:** 2026-06-15
- **md_twin:** /glossary/agent-card.md