Centralized Authentication Architecture With Shared Auth Package

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