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I'm wrinting the documentation for a tool API (for my game AF8) and I don't know what the `uses` in the tooldef really do.
So I looked into the lua_api.txt, but didn't found anything that explains it, so I'm writing this topic. :D

e.g. if uses = 8 you can dig even more than 8 nodes...
Can somebody explain this? (then this also could be added to the lua_api.txt)

It is in lua_api.txt

https://github.com/minetest/minetest/blob/master/doc/lua_api.txt#L1277

TLDR; It is the maximum no of nodes at the tools level that it can mine. If the nodes are at a lower level, it can mine more.