If it's painted, you are cleaning the paint, not the aluminum. Think of it like your car or truck: it has aluminum, plastic and steel panels, but they are painted, so you clean & polish the paint, not the material underneath.
Next question: is it dirty or is it faded or is it scratched? The answer is what dictates the proper product to use. If it's just dirty, any boat or car wash will work fine. You can actually apply a protective coat of polish afterwards to help keep it clean.
If it's faded or scratched, you might want to use a cleaner wax to help restore it, but be careful, as I doubt the layer of paint is very thick. Any overly aggressive use of a cleaner wax or a compound could easily strip off the remainign paint.
You might be best off to clean the tool box and then repaint it with an appropriate paint.