A2A Reference

The reference pages answer one narrow question each and are built to be scanned. They sit next to the Core Objects pages, which explain how things work, and the Specification , which gives the complete rules.

PageRead this when
A2A Error CodesYou received an A2A error, or you implement error handling in a server or client
Agent Card Proto Field NumbersYou work with generated protobuf code, or migrate a card or SDK from v0.3 to v1.0

Each page states which version it was checked against and links its sources. Where the official documents disagree with each other, the page says so and follows a2a.proto, which the specification names as the normative definition.

Source: A2A official specification and a2a.proto