[Ranama]

If you mean like error message if the player type a command that don't exist try using this, that's what i use (I'm using YCMD):

Код:

public OnPlayerCommandPerformed(playerid, cmdtext[], success){
if(success == 0)return SendClientMessage(playerid, COLOR_GRAY2, "SERVER: Unknown command, use /help for further help.");//If player writes command wrong this will still return it as a true.
}

Hope it helped, otherwise describe more thanks