When Does the A2A Protocol Actually Matter?

What this post added

Introduces the Agent-to-Agent (A2A) protocol, defining its primitives (Agent Card, Task, Message, Part, Artifact) and its role as a framework-agnostic wire protocol for inter-agent communication. It establishes the core decision criteria for adopting A2A: whether agents cross genuine ownership or trust boundaries. The post details A2A's security model, emphasizing transport-layer security, external authentication/authorization, and the Agent Card's role in declaring supported schemes. It discusses the challenges of delegated permissions and the reliance on external identity providers and OAuth for managing reduced-scope access. The post also contrasts A2A with the Model Context Protocol (MCP) regarding authorization and touches on the current state of A2A adoption and its architectural implications.