A2A Protocol Hits v1.0: What Changes Now That Agent-to-Agent Communication Has a Stable Standard

Google's Agent-to-Agent Protocol reached v1.0 on March 12, 2026 — the first stable, production-ready release. With gRPC support, signed Agent Cards, multi-tenancy, SDKs in five languages, and integrations from Microsoft Azure, AWS Bedrock, and Google Cloud, A2A is the consensus standard. IBM's ACP merged in, AP2 adds payment rails, and 150+ organizations are on board. Here's what v1.0 includes, what broke from 0.3, and what it means for teams building multi-agent systems.