Employees use AI tools anyway, often without guidelines. An AI policy makes it clear what applies, so that nobody has to guess. It does not need to be long. One page that everyone reads beats twenty that nobody reads.
A good policy answers a few questions: which tools are approved, which information must never be entered, how the answers should be checked and who to ask when something is unclear.
The policy goes together with AI literacy. Only when the staff understand why the rules exist will they follow them.