Okay i solved the problem! just run vcredist.exe go to your C:\Program Files (x86)\Steam\steamapps\common\call of duty black ops III\_CommonRedist\vcredist\2012 then run the application for whichever your system is x64 or x86 then start up radiant it will work!!!!!
when ever i try to start radiant map editor it hits me with that error. i reinstalled the tools and through steam i tried to verify my black ops 3 game and mod tools cache files. i don't know what else to do.