Agent Card

Discover An Agent Card is a JSON document that an A2A server publishes to describe itself to other agents: its identity (name, description, provider), its service endpoint URL, the A2A capabilities it supports (streaming, push notifications), its authentication schemes, and the skills it offers, each with an id, description, and input/output modes. A client agent fetches a card before talking to a server so it can decide whether to use it and how to structure requests. The recommended discovery mechanism is a well-known URI, /.well-known/agent-card.json, following RFC 8615, though curated registries and direct configuration are also defined discovery strategies. Cards can also be served behind authentication when they carry sensitive detail, using an "authenticated extended" variant. This is A2A's own discovery object; it is distinct from an MCP server card, which describes an MCP server rather than an A2A agent. Used by: a2a.