You're building an agent that helps a team plan Java upgrades. Someone asks it which Spring Boot version first required Java 17.

It doesn't know. Another agent does.

That agent belongs to another team. It runs on another server. Maybe it was built with another framework.

Skills won't help here. Neither will subagents. Both live inside your agent, in your workflow, on your server.

You need a protocol neither side owns. That's A2A (Agent2Agent): an open protocol for agents to find each other and hand over work, across frameworks and vendors.

Here's how it works, and how we run both sides of it in ByteChef , an open-source workflow automation and AI agent platform built on Java and Spring.

A2A in three ideas

The Spring AI team covers agents working across system boundaries in their A2A post . The protocol comes down to three things:

The agent card. Every A2A agent publishes a small JSON document at /.well-known/agent-card.json with its name, description, and skills.…