This tool is used to verify your status as a trader and also to make sure the OMM you are working with is not a fake and is in fact the real deal.
What happens is a trade is requested with an OMM, and using an extension of MPGH they can give you a personalized code just for you that can do simple checks such as are you blacklisted in any of the stickied threads in any BST section. Simple stuff that can reduce scams. Only legitimate OMMs have the ability to generate these codes, and they are impossible to fake in any way. If someone provides you with a fake code, it will fail to authorize. Simple as that.