The Agent2Agent protocol, or A2A, is an open specification for communication among agent systems that may use different frameworks or be operated by different vendors. It defines common ways to describe capabilities, exchange information and manage collaborative tasks without revealing every agent's internal design.
A system can publish an agent card describing its available capabilities and connection details. Other systems can discover that card and exchange task-related messages through the supported protocol. This is distinct from the Model Context Protocol, which commonly connects AI applications to tools and data sources.
A2A makes interoperability possible, but it does not make an agent trustworthy or guarantee that the agents will succeed. Authentication, authorization, transport security, validation of received content and limits on side-effecting actions remain necessary. Different implementations may support different protocol features.
When integrating agents, check the specification version used at each endpoint, test how failures and cancellations propagate, and avoid giving a remote agent broader permissions than its task requires.