I learn you about a MCreator easter egg.
In MCreator (no codding) you no change the creative tab of the tool. Automatically, the item goes to Tools tab.
To place the tool to the tab you want, in the button, on top of ItemRegistry, clear the ; and write: .setCreativeTab(XXX.tab);
XXX - write the name of the tab (do not forget mcreator_ the first word used of the name is tiny the firt letter of the first word!).