‘I don’t know’ can be a responsible answer. The difficulty is that the recipient may still need to decide what to do next. You can make uncertainty useful by explaining its boundary.
Try: ‘The draft is complete, but I haven’t checked the figures yet. I can’t confirm the final version until that review is done.’ This separates a known status from an unresolved condition.
If you can offer a next step, make it one you actually control: ‘I’ll check whether the figures are available this afternoon.’ Avoid replacing an unknown result with an optimistic promise such as ‘It should definitely be fine.’
There are different kinds of uncertainty. You may lack information, need someone else’s decision or be unsure of your own preference. Naming the kind helps the other person respond. ‘I need the supplier’s confirmation’ is different from ‘I haven’t decided which option I prefer.’
An AI draft should preserve these distinctions. Smooth language should not turn a tentative estimate into a commitment.
Before you send an uncertain answer, ask whether the reader can tell what is settled and what could still change. Clear uncertainty can support planning. Artificial certainty may only postpone the difficult conversation until the promise cannot be kept.