Reference

A2A

Agent-to-agent handoff carries a delegation chain. Authority does not travel with the task; it is re-established by the receiving service.

Agent Card

Published at /.well-known/agent-card.json. It describes capabilities, input modes, and authentication requirements. It does not grant access.

{
  "name": "AdBid Control Agent",
  "version": "1.0",
  "capabilities": ["campaign.plan", "decision.preview", "receipt.read"],
  "authentication": { "schemes": ["bearer"] },
  "delegation": { "supported": true, "max_depth": 2 }
}

Task handoff

A delegated task records the initiating principal, the delegation chain, the exact scope, and an expiry. The receiver re-authorizes every operation. A2A task state is separate from the financial task ledger and must reconcile to it.