A sentence is plenty. "An app that tracks how much water my dog drinks" works better than a product name or a pitch, because we are trying to guess what a shopper types — and a shopper does not know your product name.
The one thing worth being specific about is the subject. "A better habit app" gives us almost nothing to look up; "a habit tracker for people who work night shifts" gives us several real phrases.
If nothing searchable can be pulled out of what you wrote, we say so rather than guessing, and you can rephrase and try again without it costing you a report.