How will liquid nitrogen affect a steel instrument's ability to function? I want to retrieve cryotubes from the bottom of a liquid nitrogen freezer without taking all the freezer racks out and draining the liquid nitrogen. I think I can accomplish this using a tool like this but I am not sure how well the tool will function at temperatures as low as -160 Celsius. Also, this particular tool is probably only about half as long as it needs to be. 

Assuming I can find a longer version of such a tool, how can I determine whether or not I need to be concerned about using to retrieve cryotubes from a liquid nitrogen freezer? My main worry is that parts of the tool may become brittle and break or that the claw's ability grab may somehow become compromised. I am not concerned about the metal becoming excessively cold because I will be wearing gloves intended for such work. 

Is there a chart or other resource that I can use to get a sense of metal's shear strength at cold temperatures?
Metals become brittle as low temperature (and that's why you cool your Parr bomb in a dry ice bath, never in liquid nitrogen when you condense gases in).  But the worst thing that can happen is that a claw might break off, which shouldn't cause any damage to equipment.  Why not try in a small dewar first.  Liquid nitrogen is cheap.

A good alternative to racks of storage boxes are storage canes, such as these.