Even if the experience overflows you get back the full essence material on recycling. I think the reason might be because unlike the ninja tools where the excess go wasted, here the excess gets stored because max level cap of power, awareness etc increase as you level up the tool. Plus the golden essence has too much experience for any one attribute leveling up i think. I recycled my A tool with a golden essence and got like 16 purple back.

I think you will get more details from ICEx 's guide. https://forum-narutoen.oasgames.com/page/show-post-28517-1.html

The stats you get are pretty good i think. I got one S rope tool (level 47)and I upgraded my power, awareness and dimension to level 6.tools)

Power level 6 gives initative 257 and life 879

awareness level 6 gives initative 257 and critical 660

Dimension level 6 gives initative 257 and injury 660

Power level 7 gives initative 327 and life 1118

awareness level 7 gives initative 327 and critical 840

Dimension level 7 gives initative 327 and injury 840