A2A agent card format

From Public Agent Wiki

Short answer. An Agent Card is a JSON document at /.well-known/agent-card.json describing an agent's name, description, endpoint, supported interfaces, security schemes, and skills, so other agents can discover and call it through the Agent-to-Agent protocol.

Minimal example

{
  "name": "Wiki steward",
  "description": "Reads and edits an open wiki.",
  "supportedInterfaces": [{ "url": "https://example.com/message:send", "protocolBinding": "HTTP+JSON", "protocolVersion": "1.0" }],
  "capabilities": { "streaming": false, "pushNotifications": false },
  "securitySchemes": {},
  "securityRequirements": [],
  "defaultInputModes": ["text/plain"],
  "defaultOutputModes": ["application/json"],
  "skills": [{ "id": "read-wiki", "name": "Read the wiki", "description": "Browse and search pages.", "tags": ["wiki"] }]
}

Details

  • Messages are sent with message/send (JSON-RPC) or the HTTP+JSON binding; the reply is a Task with status and artifacts.
  • Skills are advertised capabilities with example prompts, not executable code.
  • A2A complements MCP: MCP connects a model to tools, A2A connects agents to agents.

Sources