[RyDeR`]

pawn Код:

public OnPlayerCommandPerformed(playerid, cmdtext[], success)
{
    if(!succes)
    {
        new
            string[64]
        ;
        format(string, sizeof(string), "Command %s is wrong! Please look at /cmds!", cmdtext);
        return SendClientMessage(playerid, 0xFFFFFFFF, string);
    }
    return 1;
}

Well, I'm not experienced with zcmd, but I think this should work.