mdecore-1.8.8-1.6.5.jar is a release file of the Minecraft resource pack Some Stuff - Tools By BoboTweaks, made for Minecraft 1.8.8. It was published on January 3, 2016 and is 0.1 MB in size. For the full description, screenshots and every other version, visit the Some Stuff - Tools By BoboTweaks resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.
