Why typing.Annotated?

I chose to use typing.Annotated to attach metadata to types instead of using custom classes to avoid cluttering the object model. The Python community has been slowly moving away from arbitrary mix-in classes to a purer form of OOP. Personally, I care less about OOP purity and more about using the right tool for the job. In this case, I am attaching descriptive metadata to types so using typing.Annotated is the right tool for the job. If I were providing functionality that is used inside of an application class, then I would use a mix-in class. The goal is to keep the application's object model clean.