There's nothing wrong with returning something well-specified from toString, but I agree this should never be relied upon. And even if toString actually return something well-specified, the same functionality should be available as a distinct method.

Any form of (semi-)automatic SomeObject -> String should be treated as a convenience for the developer to avoid getting a non-descriptive memory location reported.

Having the automatic toString isn't the problem, but maybe the name of the method is. It could be called "asDebugHelpRepresentation" or something more descriptive.