The problem is quite literately, it's text. Having the description is nice, when it's in the "skill window" but you don't have time to read the tool tip when you're actually using it. What you basically need is iconography that matches what the game uses and an icon for "COMBO WITH"(green circle icon in corner) and "OVERWRITES" (eg a red Octogon on the skill icon it can't be used with).
Heck an argument can be made that the tool tips during combat are absolutely useless because when they pop up, they cover everything near it, so knowing if that skill can be combo'd with when you can't see it, isn't helpful either.