Mis Cis, isn't it?
Right
Any plans to use that for making another custom tool for your set?
No, not so far. Currently there is no need for another tool
And I only have the green tool once, which is needed to make the bike workshop complete.
And looking closely at the images, they look like the handles are different, and the yellow tool may be a combination of the blue and green tools...
Yes, you're right, the yellow one is a multi-tool combination of the other both. Probably a cost reduction measure of Playmobil (or just a convenience issue, not wanting to change the tool that frequently when dealing with System-X stuff).