Recent studies have focused on characterizing bacterial cell-size control strategies from single-cell measurements. It remains largely unknown, however, which are the underlying bio-molecular mechanisms of such strategies. We extend recently proposed modeling approaches to study cell-size control phenomena. We propose model signatures that might shed light on key components that a bio-molecular mechanisms should include to explain a given cell-size control strategy. Understanding such bio-molecular mechanisms are key on crucial applications like medicine, epidemics, and industry.