What Is Agent-to-Agent (A2A)?
Agent-to-Agent (A2A) is an open standard for how independent AI agents discover one another and communicate — advertising what they can do through an agent card and exchanging tasks and messages. Where MCP gives one agent access to tools, A2A lets separate agents find and coordinate with each other, which is what a web of many agents from many organisations requires.
How agents find each other
A2A gives an agent a card that describes its skills and how to reach it, commonly discovered at a well-known path, so another agent can learn what it does and hand it work. It addresses discovery and messaging between peers; like MCP it leaves organisational accountability — identity, authority, proof — to layers built for that.
Related standards
Questions
Is A2A a competitor to MCP?
No. They are complementary: MCP connects an agent to tools; A2A connects agents to each other. A full system uses both.
Where does an A2A agent card live?
Commonly at a well-known path on the agent’s domain, so a peer can discover it without prior configuration.
Keep reading
By Michael Gord · published 2026-09-29 · part of the Agentic Encyclopedia. Dates are the day of publication; events are cited at their own dates.