Tailor your handoff detail to your team. Experienced front-end developers may need less annotation than a team new to your design system. Ask them what they need.
Strong answers mention: annotated designs with spacing and interaction specs, component references to the design system, edge case documentation, interaction states, responsive behaviour notes, and accessible implementation guidance. Best candidates discuss finding the right level of detail for their team rather than over-documenting.
Practical skill that directly impacts implementation quality. Over-documentation wastes time; under-documentation causes back-and-forth. Ask to see an example of their handoff documentation.