In the Skillcape Guide, on the section giving information about Skillcapes Skill Bonuses, it says:

 

Do the capes do anything else you ask? Of course they do. A little flash isn't all that useful and rewarding is it? If you put on the cape, the matching skill's max level will increase to 100. Alternately, you can right click the cape if you are wearing it and click operate. How is this helpful? A 1 level difference can be helpful in completing tasks. Lose your cooking gauntlets? You will burn next to no sharks at 100 cooking! There are many other uses for it as well, such as rune mining in the wilderness, or fishing sharks. The higher your level, the easier it is to get these hard to obtain materials. If you have a cape for a skill that having 100 in does not make any difference, it is still wonderful to see one of your stats in the triple digits without drinking a potion.

 

Since a while (I don't know how long), if you right-click the cape while wearing it, it says "Boost" in stead of "Operate".

 

Just a stupid detail of course :P

Thank you redtiger63, I just checked this with my defence cape and you're correct. I've made the changes, credited you and the changes should be reflected soon. :)

 

~Aura