Agent Client Protocol (ACP)

With already https://agentcommunicationprotocol.dev (ACP) same name seems confusing now. even though differences are there in both.

IBM announced in March 2025 its Agent Communication Protocol (ACP) but is now abandoning the ACP name and merging ACP efforts with Google’s Agent2Agent (A2A) protocol at the Linux Foundation. The ACP team is winding down as the industry backs A2A for open, community-driven AI agent interoperability under Linux Foundation governance. This move aims to unify protocols and avoid fragmentation in AI agent standards.

https://lfaidata.foundation/communityblog/2025/08/29/acp-joi...

That seems odd. Even with an A2A protocol, don’t you still need to standardize a client “surface” or “API” or whatever, so agents can describe IDE actions they want to trigger in the expected terms over that protocol?

Or is A2A like USB, where it acts as both a registry of, and “standardized standardization process” for, suites of concrete message types for each use-case?

Like, yeah, when a "client" drives an "agent", that's no different than what any generic "agent" would be doing to drive an "agent"; an IDE or what-have-you can just act as the "parent agent" in that context.

But when an "agent" is driving a "client", that's all about the "agent" understanding that the "client" isn't just some generic token-driven inference process, but an actual bundle of algorithms that does certain concrete things, and has to be spoken to a certain way to get it to do those concrete things.

I had assumed that IBM's older ACP was in large part concerned with formalizing that side of interoperation. Am I wrong?