How do you do requirements well?

Poorly defined requirements cause serious problems for my team – disagreement, bike-shedding, waste, re-work. Normally it’s because requirements come in from the business via a BA or PO, that are poorly defined from a business need POV and insufficient for implementation due to ambiguity, being oversized, focused solely on the user and not on system behaviours or constraints, limited to functional vs. non-functional. What does requirements discovery and definition best practice look like re process and tooling?