Understanding your emotional attachment to the offer is even more important than the data. Ideally, you want low emotional attachment and high data (as explained in this Taro blog post by Rora).
For example, don't reveal that you're only talking to a single company, or that you're talking to 30 (either extreme can hurt you). Sample dialog:
If anything changes on my end, I’ll let you know, but for now I’m eager to learn more about your company
(There's a whole section dedicated to helpful phrases later on.)
You can share information with the recruiter, but be mindful of what and when you share. How much PTO or signing bonus you want are topics that should come up before (if it's a blocker) and after the interview, not during.
If in doubt, don’t share it. Just be positive and non-committal to pretty much everything the recruiter says. Answer questions with vague responses and be confident.