Minecraft Wiki:Sandbox

Limitations
@Brigadier:

Brigadier is not reliable as the hack-mastering-like library (like Java source code modifications for cheats-only usage). Brigadier has some limitations for some commands like, resulting in execution failure, but the further future command libraries other than Brigadier will be worked further functionally.

Due to the bug in Brigadier, command suggestions reports "Incorrect argument" with a trailing whitespace without suggestions (MC-165562), and command syntax checks whitespaces, etc. In fact, the leading whitespaces and extraneous slashes (e.g. //) should also be ignored before command names.

In some commands (mostly, ), Brigadier still use 32-bit IEEE floating-point for certain arguments which can cause the great numeric imprecision and range limitations.