Protocols

This page is documentation, not research and not a decision. It is an orientation, not a specification: it names the protocol interfaces Cortxt relates to and states which of them Cortxt has adopted, without restating their specifications. Where this page and an Accepted ADR disagree, the ADR wins.

ACP — Agent Client Protocol

ADR-047 adopts the Agent Client Protocol (agentclientprotocol.com) as an ACP client: Cortxt drives ACP-speaking agents over the protocol instead of over per-adapter subprocess conventions. Exposing Cortxt as an ACP agent is deferred, not rejected.

As verified by the ADR at the time of adoption: v1 is stable, v2 is in draft, local transport is JSON-RPC over stdio, and remote transport over HTTP/WebSocket is stated by the upstream project to be work in progress.

A naming warning that matters. “ACP” has referred to two different protocols. The one Cortxt adopts is the Agent Client Protocol above. A separate Agent Communication Protocol (IBM BeeAI, i-am-bee/acp) was previously conflated under the same label; it is archived and is not adopted by Cortxt. ADR-047 pins the label on that two-distinct-protocol basis.

ADR-047 also separates three levels that had been discussed as one thing: the client-to-agent protocol (adopted), the result channel carrying a worker’s outcome (derived), and the cross-process coordination plane (built). They are one gap, but they are not one decision.

MCP — Model Context Protocol

ADR-024 decides that Cortxt’s external integration surface takes the form of an MCP server, rather than an SDK or a REST API, for the initial slice.

A2A — Agent2Agent

A2A is the Linux Foundation protocol that the archived Agent Communication Protocol became part of. It is named here because the “ACP” name collision makes the lineage necessary to state. ADR-047 does not adopt A2A, and no Cortxt A2A integration is documented.

What this page does not claim

This page does not describe transports, message schemas or implementation state for these protocols beyond what the cited ADRs state. It is not a compatibility statement and not a roadmap.