You are not sure what the roof needs
Plenty of roofs never announce their problems. The roof is getting older, a storm came through last week, there are granules in the gutter, or the house next door just got a new roof. None of that tells you what your own roof needs.
The free inspection is for exactly that. A roofer walks the roof and looks at the shingles up close, then at the places where they are interrupted: pipes, vents, walls, valleys and the edges. After hail or high wind the same walk looks for creased tabs, missing shingles, bruised spots and dented metal. The answer may be a repair, a replacement or nothing at all, and a roof in good shape gets called that.
Storm work has one extra wrinkle. What a roofer finds on the roof and what an insurance policy covers are separate questions, answered by different people. The storm damage page explains how the two fit together.