Better Commands adds various shortcuts for other commands to make using them easier and faster.
List of commands and/or shortcuts Better Commands adds (At time of first release for 1.15.2)
Shorter gamemode commands. (/gmc, /gms, /gmsp, /gma)
Gamemode swapper item and keybind. (Keybind is G by default)
Time changer item.
/heal command an heal item.
/fly command and item for survival mode.
/clearlag command and item shortcut for it.
Gamerule panel.
Shortcut for giving a command block. (/givecmd)
List of entities that the /clearlag command removes:
Items
Boats
Thrown Items
Arrows and Spectral Arrows
Area Effect Clouds
XP Orbs
Falling Blocks
I very likely plan on updating this and/or porting it to other versions.
If you have any suggestions feel free to level them in the comments.
