Does ACP replace MCP?

No. ACP is the editor session. MCP is the tool/context bus. Official architecture even shows the editor forwarding MCP server configs into the agent, including a small proxy when the agent only speaks MCP-over-stdio.

Why does this website call itself ACP Server?

It is an independent landing page at acpserver.org. In protocol talk, the “server” is usually the agent process. This site is not a hosted agent and not the official specification.

Disambiguation

ACP vs MCP vs LSP (and the other ACPs)

If a search result says “ACP”, it might not mean this protocol. Agent Client Protocol is the editor↔coding-agent standard. It composes with MCP; it does not replace it.

Layer comparison

Protocol	Connects	Shape	Status
ACP (Agent Client Protocol)	Editor / client ↔ coding agent	JSON-RPC, stdio first	v1 stable, v2 draft
MCP (Model Context Protocol)	Agent / model ↔ tools, data, prompts	JSON-RPC client/server	Linux Foundation / AAIF
LSP (Language Server Protocol)	Editor ↔ language server	JSON-RPC over stdio	Stable, Microsoft-originated
A2A (Agent-to-Agent)	Agent ↔ agent across systems	Task/peer protocol	Linux Foundation

How they fit together

You stay in the editor (ACP client). The editor starts or connects to a coding agent (ACP). That agent calls MCP servers for tools and context — often ones the editor already configured, passed through session/new. LSP still handles completions and diagnostics. A2A is a different plane: agents talking to other agents, not to your IDE.

Same letters, different protocols

Agent Client Protocol (this site)

Created around Zed’s external-agent work, now community-governed at github.com/agentclientprotocol. Apache licensed. This is the protocol acpserver.org covers.

IBM Agent Communication Protocol (retired)

A REST agent-to-agent protocol for BeeAI. Donated to the Linux Foundation, then merged into A2A in August 2025. The repository is archived. Do not implement it for new work.

Agentic Commerce Protocol (OpenAI / Stripe)

A checkout and commerce standard for AI agents that buy things. Unrelated to code editors. If you needed payments, you are on the wrong page.

Agent Control Protocol and others

Research and vendor projects reuse the acronym for authorization or governance layers. They are not wire-compatible with Agent Client Protocol.

Which one do I implement?

I am building an editor, TUI, or chat host for coding agents

Implement an ACP client. Speak v1.

I am building a coding agent

Implement an ACP agent, then optionally list it in the registry. Use MCP for tools.