Let me revive the thread. As a way to verify the design and the implementation I added Annotated-based markers to Injector (I’ve done it quickly before, now I fully tested it and did it right). https://github.com/alecthomas/injector/commit/d50e581734d6673ab0a2d9de7ccf09... if anyone’s interested. I want to release it soon. It was rather trivial, with the exception of testing if an object is an instance of Annotated – but once get_origin works with Annotated this won’t be an issue. I wanted to test mypy integration and I found an issue with aliasing I think, reported here: https://github.com/python/mypy/issues/7729 All in all the typing_extensions implementation seems to be working nicely and this PEP satisfies my needs so far. Best, Jakub