What is it supposed to be for?
I can't even guess, either from the picture or the term "hanger tool"
Straightening your rear mech hanger when you bend it
So why is it fixed to the handlebars?
So why is it fixed to the handlebars?
And wouldn't a mole or adjustable spanner and a vice be easier
Several YT channels have featured this recently - even Calvin at Park Tool. You can use the hanger tool to check that your brifters as aligned in both height, angle and distance potentially alleviating discomfort when riding.
So does this one have a means to attach it to the top of the steerer? Mine only has de M10 bolt.