[xAndrewx]

function onActionServerside(option) {
  if (temp.option == "createGuild") {  
    temp.guildName = player.chat.substring(9).trim();
    addGuildMember(temp.guildName, player.account, player.nick);

    player.chat = "Created guild:" SPC temp.guildName @ "!";
    player.guild = temp.guildName;
  }
}
//#CLIENTSIDE
function onPlayerChats() {
  if (player.chat.starts("/addGuild")) {
    triggerserver("weapon", this.name, "createGuild");
  }
}

You might want to actually check if the guild already exists