Authentication And Authorization Framework With Pluggable Auth Backends

via “security and authentication framework with pluggable schemes”

Agent2Agent (A2A) is an open protocol enabling communication and interoperability between opaque agentic applications.

Unique: Defines authentication as a protocol-level concern with pluggable schemes declared in AgentCard, rather than leaving it to framework implementations — enabling agents to negotiate security requirements during discovery and enforce them consistently across all protocol bindings

vs others: More flexible than single-scheme approaches (OAuth-only, mTLS-only) and more discoverable than implicit authentication, providing standardized security negotiation that works across heterogeneous agent deployments