Try reading this before you make the adjustment on your rear derailleur. https://www.sheldonbrown.com/derailer-adjustment.html The only tool you need to make adjustments on a rear derailleur are a Philips head screwdriver and the proper size hex wrench if you need to adjust the length of the derailleur cable beyond what you can do with the adjustment at the end of the cable where it enters the rear derailleur.