Comment by benswerd

MCP Auth is just Oauth, its designed for humans to authenticate their sessions for connections.

TBH I know nothing about A2A.

Agent Identity and Authz is a different problem, allowing agents to operate independently from humans with granular permissions is coming/whether from these protocols or others, and when it does I think CLIs/CLI Device Auth which is used as a rough proxy for this where the agent just takes your identity will finally go away.