Alan W.wrote a review of Shimano TL-EW02 Di2 Wire Connecting Installation Tool on July 27, 2019
Familiarity: I've used it once or twice and have initial impressions
If you have a thumb and pointer finger this tool is totally unnecessary. I thought that the plugs had some special locking device, NOPE. The plugs just snap on and off.
Please ignore this review if you are an amputee or dog. You will need the too than.