Design Documentation
With design documentation, it’s difficult to discern what is too little and what is too much. While It’s a waste of time to redline every single element in a comp, a developer should never have to guess at anything. Getting the balance right depends on a few variables: the effectiveness of the design system in place, the experience and knowledge of the designers and developers, and the extent to which previously built components are referrencable.
At the very least, design documentation in specific agile tasks should define anything novel not yet established in the product. This work is the designer’s responsibility. The developer, however, needs to know enough about the design system and the rest of the product to be sure they are following established patterns. There is a natural give-and-take here which needs to be worked out between designers and developers. No two product teams will have the exact same balance.
My attitude is always to accept 100% of the responsibility in situations like these. As a designer, assume the developer needs you to be highly detailed in your documentation. Be thorough at the start, and later discern where you can lean on your growing design system.