How to make a script like this undetctable.

I am currently looking for a way not go get caught using an auto healing scipt for a text based game. Here is the script code. I will not give the website name.

// ==UserScript==
 // @name   Auto eat script
 // @namespace          
 // @author   Private
 // @include   http://www.xxx.com/game.php
 // @version   1.3a
 // @description   Auto heals.
// ==/UserScript==


var autoEat = true;
var foodId = 34071864;
var minHp = 15;
var messageChannel = 5;

function checkHps() {
 if (needToEat()) {
  message("*********Auto eating food***********");
  unsafeWindow.useItem(foodId, 'F');
 }
 if (autoEat) setTimeout(checkHps, 4000);
}

function needToEat() {
 var hps = getHps();
 return hps<minHp;
}

function getHps() {
 var hps = parseInt(unsafeWindow.$('statsHPText').innerHTML);
 //message("Hps: "+hps);
 return hps;
}

function message(txt) {
 unsafeWindow.addChat(messageChannel, txt);
}

if (autoEat) checkHps();
unsafeWindow.messagePopup("Auto eating script","Active!");