Optional: a two or three-line description of the class here would be very helpful. What is this, for what is it used for, when it's used?

I know that this is obvious for you, and one could argue it is redundant information, but I really think the benefits outweights the small bit of redundancy: for someone not used to the patch, this description would easy the understanding a lot. It also serves as a guideline for others changing this code in the future, e.g. "if what I'm adding will make the class comment wrong, is that the right change?"