There is an old completed suggestion at #817 about adding tooltips when the variable name is too long for the widget that would give the full variable name. That doesn't appear to have been implemented.

More than this though, I think it would be good to have something that is not the variable name at all, but more like a short note. I will have comments in the code giving a note about what each variable does but that doesn't really help the person who is using the slider.