Agent Card
Definition
A machine-readable JSON metadata file (typically hosted at /.well-known/agent.json) that describes an agent's capabilities, supported protocols, authentication requirements, and operational constraints. Agent Cards enable capability discovery — allowing other agents and systems to understand what an agent can do before attempting to interact with it. Defined as part of the A2A protocol specification.
Builder Context
Even if you don't adopt full A2A, publishing an Agent Card for your agent is valuable. It serves as a machine-readable API contract that other agents can discover automatically. Include: supported input/output formats, rate limits, authentication method, and a human-readable description of what the agent does. Think of it as a robots.txt for agent interoperability.