Agent2Agent Protocol vs Agent Communication Protocol
The map lists them as complementary: sites and agents commonly implement both.
| Agent2Agent Protocol A2A | 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://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 It is no longer maintained; prefer its successor.
Read the full articles
- Agent2Agent Protocol: How do two independent agents, built on different frameworks, discover each other and delegate a task to completion?
- Agent Communication Protocol: How did agents, applications, and people exchange multimodal REST messages before merging into A2A?