Agent to Agent Protocol (A2A)

How do AI agents talk to each other?

Agent to Agent Protocol (A2A) from Google provides structured communication flows for autonomous systems to coordinate, delegate tasks, and collaborate without human intermediaries.

A2A vs MCP

Aspect	MCP	A2A
Focus	Tool use — agent ↔ external capability	Agent ↔ agent communication
Scope	How agents access tools	How agents coordinate
Analogy	HTTP (accessing resources)	TCP (establishing connections)

They're complementary: MCP for tool access, A2A for inter-agent coordination.

Resources

• A2A GitHub
• A2A vs MCP
• Google Developer Blog: A New Era of Agent Interoperability

Context

• Agent Protocols — The protocol landscape
• MCP — Model Context Protocol for tool use
• Agent Commerce — Transaction protocol
• Protocols — What protocols are