Required information:
Minecraft Version: 1.20.4
Mod Version: v1.1.1

I am unable to add enchanted books to tools on anvils when using this mod.
This happens for any level of any kind of book that is compatible with the tool, and makes books effectively useless past the discovery aspect.
Am i missing a mechanic or something, or is this a bug?

This is stated as a mechanic on the mod page

This is changed in the most recent version(1.2.0). You can enchant stuff in anvil using books again