What is the Agent2Agent Protocol (A2A)?
Last verified 2026-06-10The Agent2Agent Protocol (A2A) is an open standard for communication between AI agents, announced by Google on 9 April 2025 with support from more than 50 technology partners and donated to the Linux Foundation on 23 June 2025. It lets agents built by different vendors and on different frameworks discover each other, delegate tasks and coordinate work, without exposing internal memory, tools or proprietary logic. A2A is complementary to MCP: MCP connects an agent to its tools and data, A2A connects agents to each other. In the commerce stack, AP2 is designed as an extension of A2A, and crypto payments flow through the A2A x402 extension. The specification (v1.0) and official SDKs are published at a2a-protocol.org under Apache 2.0, governed by the Linux Foundation Agent2Agent project.
Key facts
| Author / steward | Created by Google; now a Linux Foundation project |
|---|---|
| Announced | 2025-04-09 |
| License | Apache 2.0 |
| Governance | Linux Foundation Agent2Agent project (announced 23 June 2025 with Amazon Web Services, Cisco, Google, Microsoft, Salesforce, SAP and ServiceNow) |
| Scope | Open standard for agent-to-agent communication: lets AI agents from different vendors and frameworks discover each other, delegate tasks and coordinate work; complementary to MCP (agent-to-tool) |
| Transport | HTTP-based protocol; specification v1.0 and SDKs (Python, JavaScript, Java, C#, Go) published at a2a-protocol.org |
| Payment | None (not a payment protocol); AP2 is designed as an extension of A2A, and crypto payments flow through the A2A x402 extension |
| Maturity | donated |
What makes it distinctive
- Announced by Google on 9 April 2025 with support from more than 50 technology partners
- Donated to the Linux Foundation on 23 June 2025 (Agent2Agent project with AWS, Cisco, Google, Microsoft, Salesforce, SAP, ServiceNow)
- Specification v1.0 published, with official SDKs in Python, JavaScript, Java, C# and Go
- Agents collaborate without exposing internal memory, tools or proprietary logic
- Complementary to MCP: A2A is agent-to-agent, MCP is agent-to-tool
- Foundation layer for AP2 (payments) and the A2A x402 extension (crypto)
How A2A works
A2A standardizes communication between agents. A client agent can discover a remote agent, delegate a sub-task, exchange information and coordinate actions, while each agent remains opaque: it does not expose its internal memory, tools or proprietary logic. This lets agents built on different frameworks (the project cites LangGraph, CrewAI, Semantic Kernel, custom stacks) interoperate. The project documents core concepts such as the life of a task, agent discovery, streaming and asynchronous operations, multi-tenancy, and supports extensions and custom protocol bindings.
Specification and governance
Google announced A2A on 9 April 2025 with 50+ technology partners, and donated it to the Linux Foundation on 23 June 2025; the Agent2Agent project was founded with AWS, Cisco, Google, Microsoft, Salesforce, SAP and ServiceNow. The spec has reached v1.0, under Apache 2.0, with official SDKs in Python, JavaScript, Java, C# and Go (a2a-protocol.org). IBM’s ACP (an unrelated protocol with the same acronym) was incorporated into A2A.
How A2A fits the stack
A2A and MCP are the two communication layers: MCP connects an agent to tools and data, A2A connects agents to each other. Commerce builds on top: AP2 is designed as an A2A extension, crypto payments use the A2A x402 extension, and UCP can serve capabilities over A2A.
Limitations and open questions
A2A is infrastructure, not commerce: it carries no payment or checkout semantics itself. Its commerce relevance depends on the layers built on it (AP2, UCP transport, x402 extension), so its adoption is best read through those projects.
Who should care
Enterprises running agents from multiple vendors that must cooperate, and framework authors who want interoperability without exposing internals.
Adoption
- Google: Creator (2025-04-09). source
- Amazon Web Services: Linux Foundation project member (2025-06-23). source
- Cisco: Linux Foundation project member (2025-06-23). source
- Microsoft: Linux Foundation project member (2025-06-23). source
- Salesforce: Linux Foundation project member (2025-06-23). source
- SAP: Linux Foundation project member (2025-06-23). source
- ServiceNow: Linux Foundation project member (2025-06-23). source