Agent2Agent Protocol

Google announced A2A on 9 April 2025 and contributed the project to the Linux Foundation that June. The community released version 1.0 on 12 March 2026, describing it as the first stable version. In August 2026, A2A became a hosted project of the Agentic AI Foundation, itself part of the Linux Foundation. That governance change did not create a different protocol: the versioned technical specification remains the reference for messages, tasks, bindings, and interoperability. IBM Research and BeeAI had separately maintained Agent Communication Protocol (ACP). Its maintainers announced ACP's merger into A2A on 25 August 2025 and then archived the repository. This was project succession, not wire-level identity: distinct specifications mean ACP clients are not presumed drop-in compatible with A2A.

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Enterprise workflows often span agents owned by different teams and operating in separate systems. Without a shared contract, every pair needs custom discovery, message, task-state, and authentication logic. A2A provides common concepts for capability discovery and long-running tasks, which can make cross-platform coordination easier to implement and observe. It also preserves an abstraction boundary: an agent can expose what it can do without disclosing its prompts, memory, tools, or proprietary orchestration. That boundary can support delegation while keeping local implementation choices independent.

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A procurement agent could ask a supplier agent to prepare a quote. The supplier advertises its capability through an agent card, accepts a task, reports progress while checking inventory, and returns a structured quote artifact. The procurement agent can then continue its own approval workflow without knowing how the supplier agent called models or internal systems. A simple synchronous API request is not automatically A2A: the protocol is most useful when both sides behave as agents and need shared discovery, messaging, task lifecycle, or artifact semantics.

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A2A standardizes communication, not the accuracy or trustworthiness of an agent's decisions. The specification defines authentication and authorization responsibilities, including server-side permission checks; an Agent Card is not permission to access every capability it describes. Clients and servers must also agree on supported protocol versions, bindings, and capabilities. A successful message exchange therefore does not by itself establish that the delegated task was completed correctly.

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