When trying to toggle a tool it will work the first time but afterwards whenever you reuse the command it will always say "VeinMiner successfully toggled on for tool axe" (axe example).
It doesn't toggle it off

Toggling specific categories seems to work fine but the issue seems to start happening if you have another category disabled first. In this case here you've toggled off the shovel category, but you then can't toggle off the axe category.

Can still confirm this in the 2.0.0 branch, will have a fix for this in a future update.

Kicking myself. Stupid bug lol. Fixed in the next update.

nice that was really quick! :)
cool plugin btw
I know it's random but I'm learning to make plugins myself and I was wondering what this field of programming is called?
What I mean is "is there a name for the kind of algorithms veinminer uses that I could google to learn?"

I know it's random but I'm learning to make plugins myself and I was wondering what this field of programming is called?

We generally just refer to this as "modding". We are effectively modifying how Minecraft works so it's modding :) Though in the community we'll refer to each other as "plugin authors" because it just comes more naturally

is there a name for the kind of algorithms veinminer uses that I could google to learn?

Not really. An algorithm is just some process that solves a problem, so VeinMiner uses an algorithm I came up with to calculate nearby blocks that need to be mined according to some set of rules. However if you just want to learn some general Bukkit/Spigot API, you can always browse the Spigot wiki for guides on how to make plugins, or YouTube (though take these with a grain of salt - I wouldn't follow them religiously because it's not all 1000% accurate information).

VeinMiner's code is all open source (in this repository, obviously), and the block allocation logic can be found here