Policy nobody reads changes nothing. Four agreements are usually enough to start.
Most organisations start with a twelve-page document and end up with colleagues doing it their own way anyway. Short works better, as long as it's concrete.
- What you never put in a prompt
- What you always check yourself before it goes out
- Where to go when you're unsure
- Who to report to when something goes wrong
These four points fit on one page and return in the training. You can expand later, once you see where things pinch in practice.