Then make it clear that it's "real world" and that they can and should ask questions about aspects of it that they need more information on, rather than just hoping they do so.
Usually all interviewers will say “please take some time to consider the problem and ask any clarifying questions if you have any”. This is standard for all Amazon interviews.
That feels very formulaic, which is I guess par for the course for behemoth corporations.
If it were me, I would try and frame it like "this is an attempt to be a bit more 'real-world' where we've received some initial direction on what the results are supposed to look like from management, but don't consider any of it set in stone and I'm happy to talk you through it as if we were working together...". IDK the exact verbiage, but something that gets people in that mindset without straight up telling them "this is meant to be ambiguous, wink wink".
