I was keen to start using the new 1.13 command tab completion stuff in my plugins, so I made this small API to make it easy to register argument data with the server. It allows you to do stuff like this: Hopefully at some point, a nicer API will be introduced into Bukkit to allow this data to be easily registered. At the moment though, the only way to do it is with reflection to access CraftBukkit & NMS internals. commodore just provides a nice wrapper around this. The code and usage instructions are all on GitHub. https://github.com/lucko/commodore Enjoy.