How can I make a multitool, that is ONLY pickaxe and a shovel?

Change it from a multi-tool to a special tool type

then add all of the blocks that you want it to be effective on

if you want it to be compatible with some other mods, you could make a new tag and name it stone/sand/dirt/esc and any other modded blocks with that tag will work if you add it to the effected blocks list.

ps: some mods use (Minecraft:stone/sand/dirt/esc) for there tags instead of just Stone/sand/dirt/esc so be aware of that

You can use the tag minecraft:(block name), for vanilla blocks, an if you want to use sand, stone, dirt, ect. from other mods use forge:(block type)

https://minecraft.fandom.com/wiki/Tag - scroll down for tags on every item//block

forgot to add -  mineable/shovel & mineable/pickaxe should cover most blocks.

I've got a similar issue, my special tool is able to mine a selection of blocks including stone, cobblestone, dirt and logs. When i add materials only mineable by pickaxe (such as stone or ores) to the list of breakable blocks it isnt able to mine it, is there a reasonably simple solution to this?