# Agent Client Protocol vs Agent Communication Protocol

Both belong to the Protocols called ACP group on this map. They share the acronym ACP but sit at different steps and are unrelated. They answer different questions: Agent Client Protocol is a step 5 (Act) standard, Agent Communication Protocol step 6 (Coordinate), so they are not substitutes.

[5 Act](/category/act/) [Agent Client Protocol](/protocols/agent-client-protocol/) · [6 Coordinate](/category/coordinate/) [Agent Communication Protocol](/protocols/agent-communication-protocol/)

|  | [Agent Client Protocol](/protocols/agent-client-protocol/) ACP | [Agent Communication Protocol](/protocols/agent-communication-protocol/) ACP |
| --- | --- | --- |
| Lifecycle step | 5 Act: Do something for me | 6 Coordinate: Talk to another agent |
| Answers | How does a code editor invoke and converse with an interchangeable coding agent it did not build? | How did agents, applications, and people exchange multimodal REST messages before merging into A2A? |
| Governed by | Zed Industries acts as BDFL/design-team lead over a public Request for Dialog (RFD) process; Sergey Ignatov (JetBrains) joined as a second Lead Maintainer on 2026-02-18, reflecting growing Zed/JetBrains collaboration | Formerly IBM BeeAI; archived, functionality merged into A2A under the Linux Foundation |
| Status (issuer's words) | v1 stable and shipping; v2 published in Draft form as of 2026-07-20 | "ACP is now part of A2A under the Linux Foundation" (repository banner) |
| Phase | stable | deprecated |
| Version | v1.11.0 (schema v1.25.0); v2 unstable (2026-10-09) | v1.0.3 (2025-08-21) |
| Form / transport | endpoint | endpoint |
| Found at | none fixed; local agents are launched as sub-processes, remote agents connect over HTTP or WebSocket (remote support still a work in progress) | /agents |
| Adoption | unmeasured | unmeasured |
| Evidence | 4 verified, 1 reported | 4 verified, 1 reported |
| Primary use case | Describe an agent's capabilities | Let agents talk to other agents |
| Last verified | 2026-10-19 (current) | 2026-10-19 (current) |
| Specification | [https://agentclientprotocol.com/get-started/introduction](https://agentclientprotocol.com/get-started/introduction) | [https://github.com/i-am-bee/acp](https://github.com/i-am-bee/acp) |

## When to use which

- Choose Agent Client Protocol when your question is “How does a code editor invoke and converse with an interchangeable coding agent it did not build?” and you accept its maturity: phase stable, adoption unmeasured.
- 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

- [Agent Client Protocol](/protocols/agent-client-protocol/): How does a code editor invoke and converse with an interchangeable coding agent it did not build?
- [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/).

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