Architectual pattern for CLI tool
Since your app is not very complex, I see 2 layers here:

ServerClient: it provides API for remote calls and hides any details. It knows how to access HTTP server, provide auth, deal with errors etc. It has methods like do_something_good() which anyone may call and do not care if it remote method or not.
CommandLine: it uses optparse (or argparse) to implement CLI, it may support history etc. This layer uses ServerClient to access remote service.

Both layers do not know anything about each other (only protocol like list of known methods). It will allow you to use somethign instead of HTTP Rest and CLI will still work. Or you may change CLI with batch files and HTTP should work.
I am going to write some HTTP (REST) client in Python. This will be a Command Line Interface tool with no gui. I won't use any business logic objects, no database, just using an API to communicate with the server (using Curl). Would you recommend me some architectual patterns for doing that, except for Model View Controller? 
Note: I am not asking for a design patterns like Command or Strategy. I just want to know how to segregate and decouple abstraction layers.
I think using MVC is pointless regarding the fact of not having a business logic - please correct me if I'm wrong. Please give me your suggestions!
Do you know any examples of CLI projects (in any language, not necessarily in Python) that are well maintained and with clean code?
Cheers