In MyPy, using attrs.converters gives:

error: Module has no attribute "converters"  [attr-defined]

Adding an import attrs.converters (not needed at runtime) gives:

error: Module has no attribute "optional"

I think part of the problem is the __init__.pyi isn't synced with __init__.py for importing submodules. Not sure why the star import isn't working inside converters.py, though.