Nice simple design, but I do have two recommendations.
Put plywood or something under the metal roofing, or it will get like an oven inside due to direct sunlight.
Also, if you aren’t having roosters, you don’t need nesting boxes. Chickens will happily lay eggs anywhere, and only need the box if they are going to sit on and hatch a clutch of eggs. No roosters, plenty of eggs, but no baby chicks.