Agent2Agent Protocol (A2A)
Open protocol for cross-vendor agent-to-agent collaboration in which agents publish a signed Agent Card describing identity, endpoint, and skills, and discover and verify each other before delegating tasks.
Description
A2A is an open protocol, originated by Google and donated to the Linux Foundation, for collaboration between opaque agents across vendors. Each agent publishes an Agent Card — a JSON descriptor of identity, endpoint, capabilities, and auth needs — at a well-known URL. Specification v1.0 adds Agent Card Signing (an AgentCardSignature object, JWS-based, specification section 8.4) so a client can verify a card's authenticity and issuer before binding, alongside multi-tenancy and federation.
Solution
Agent-to-agent collaboration protocol. Step 1: each agent publishes a signed Agent Card at a well-known URL describing identity, endpoint, skills, and auth. Step 2: a client agent fetches a remote agent's card and verifies its JWS signature against the issuing domain. Step 3: on a verified card, the client binds by capability and opens a task. Step 4: tasks and scoped credentials are delegated to the verified agent; messages and artifacts flow over the A2A transport.
Primary use cases
- cross-vendor agent discovery and task delegation
- verifying a remote agent's identity via a signed Agent Card before binding
- capability-based binding without hardcoded coupling
Open the full interactive page →
Diagram, neighbourhood map, code examples, related patterns and full provenance.