I created a few new materials that included the standard set of tools. The shovels I created worked fine on dirt and dirt-like blocks, but when I started using my shovel with other mods, it didn't seem to be recognized as a shovel for certain things.
One example is Ender Zoo's Khndrel Keght (or Dire Slime). With this mod, if you use a shovel to dig out dirt, the Keght doesn't spawn when dirt blocks break. If you use anything BUT a shovel, there's a chance of a Keght spawning. When I used Minecraft shovels (stone, iron, gold, diamond) the Keght never spawned. I tested by breaking hundreds of dirt blocks. When I used any of the shovels from my MCreator mod, the Keght spawned about 25% of the time, roughly the same percentage as if I used a sword or a pickaxe to break dirt.
So I thought maybe the Keght was only prevented from spawning by vanilla tools, or it was an issue with the Ender Zoo mod, so I tested this out with shovels from other mods (thermal, actually additions, and a few others) and their shovels never spawned Keghts. 100% of the dirt blocks I broke with shovels from non-MCreator mods did not spawn Keghts.
I'm wondering if this is due to how the MCreator shovels are being coded, but it looks like the ItemSpade class is being instantiated by MCreator just fine.
This can be replicated by including Ender Zoo in the mods and breaking dirt with MCreator-generated shovels vs vanilla shovels.
I don't know how this mod detects shovels, it might use ore dictionary.