1997 4-Runner brake noise

1997 Toyota 4-runner, 160K, V6 3.4L, I recently purchased this vehicle from a friend who installed new rotors and pads all the way around. It had studded tires on at this time. I got it and soon thereafter I put new rims and tires on and after that I noticed a "jangle" coming from pass. side wheel. I investigated and found on the front of the caliper (facing towards the front of the vehicle) there is a this metal bracket type thing moving around inside the exposed top of the caliper. I inserted a pic with a circle around what i am talking about. I looked at the other side and there is not one on it. My question is what is this part and what is its function? Thank you.