Instead of trying to fit people into these abstract boxes you call “job descriptions,” you should itemize the functional processes and accountabilities that actually exist in your business.
If you give people clear expectations in the form of process assignments and key performance indicators, they can measure themselves if they’ve done a good job or not.
Then it isn’t up to you to tell them (although you should) and they have an impartial metric they can believe in that enables them to feel that they’ve done a good job at their job.
And they’ll love you for it.