The bigger issue is that we need a good why to authenticate more dynamically. In the context of a desktop app (desktop claude, claude code) where you are running an application locally, for your own purposes it can run as your own user.
But when you are running things in any kind of multi-user/multi-tenant scenario, this is much harder and the protocol doesn't really address this (though also doesn't prevent us from layering something on top). As a dumb (but real) example, I don't want a web-enabled version of of an MCP plugin to have access to my company's google drive and expose that to all our chat users. That would bypass the RBAC we have. Also I don't want to bake that in at the level of the tool calls, as that can be injected. I need some side channel information on the session to have the client and server to manage that.
Ok fair enough - effectively there needs to be an authorization propagation channel that is systematic and bypasses the LLM and probabilistic layers through to each endpoint through the server. The issue isn’t the MCP server and client themselves but that there’s no clear and defined way to pass authZ through to the other side. AuthN should be handled at the interface and the AuthZ propagation is the crucial missing piece. Right?
Yep - that is my take. It isn't a weakness of MCP as such, but it a gap for which no good tooling exists afaik.