# Agent2Agent Protocol vs Agent Communication Protocol

The map lists them as complementary: sites and agents commonly implement both.

[6 Coordinate](/category/coordinate/) [Agent2Agent Protocol](/protocols/a2a/) · [6 Coordinate](/category/coordinate/) [Agent Communication Protocol](/protocols/agent-communication-protocol/)

|  | [Agent2Agent Protocol](/protocols/a2a/) A2A | [Agent Communication Protocol](/protocols/agent-communication-protocol/) ACP |
| --- | --- | --- |
| Lifecycle step | 6 Coordinate: Talk to another agent | 6 Coordinate: Talk to another agent |
| Answers | How do two independent agents, built on different frameworks, discover each other and delegate a task to completion? | How did agents, applications, and people exchange multimodal REST messages before merging into A2A? |
| Governed by | Linux Foundation; Technical Steering Committee with AWS, Cisco, Google, IBM Research, Microsoft, Salesforce, SAP, ServiceNow | Formerly IBM BeeAI; archived, functionality merged into A2A under the Linux Foundation |
| Status (issuer's words) | Stable, v1.0.0 | "ACP is now part of A2A under the Linux Foundation" (repository banner) |
| Phase | stable | deprecated |
| Version | 1.0.1 (2026-05-28) | v1.0.3 (2025-08-21) |
| Form / transport | endpoint | endpoint |
| Found at | /.well-known/agent-card.json | /agents |
| Adoption | claimed — Linux Foundation | unmeasured |
| Evidence | 4 verified, 1 reported | 4 verified, 1 reported |
| Primary use case | Let agents talk to other agents | Let agents talk to other agents |
| Last verified | 2026-10-19 (current) | 2026-10-19 (current) |
| Specification | [https://a2a-protocol.org/latest/specification/](https://a2a-protocol.org/latest/specification/) | [https://github.com/i-am-bee/acp](https://github.com/i-am-bee/acp) |

## When to use which

- Choose Agent2Agent Protocol when your question is “How do two independent agents, built on different frameworks, discover each other and delegate a task to completion?” and you accept its maturity: phase stable, adoption claimed (Linux Foundation).
- Choose Agent Communication Protocol when your question is “How did agents, applications, and people exchange multimodal REST messages before merging into A2A?” and you accept its maturity: phase deprecated, adoption unmeasured. It is no longer maintained; prefer its successor.

Guidance is derived from the two records (question, phase, adoption, prerequisites, pairings), not from opinion. Each record's page carries its numbered references.

## Read the full articles

- [Agent2Agent Protocol](/protocols/a2a/): How do two independent agents, built on different frameworks, discover each other and delegate a task to completion?
- [Agent Communication Protocol](/protocols/agent-communication-protocol/): How did agents, applications, and people exchange multimodal REST messages before merging into A2A?

Ask the MCP server to compare any two: the compare-protocols prompt, or get on both ids. [Connect](/connect/).

[a2a.json](/data/protocols/a2a.json) · [agent-communication-protocol.json](/data/protocols/agent-communication-protocol.json) · [Markdown](/compare/a2a-vs-agent-communication-protocol/index.md)