The tool in question is made of brass or bronze except for the thumb screw and is plated with some kind of sliver material. There is no lettering on the tool. Any help in identifying this unusual tool will be appreciated. Thank you.

My guess is it's part of a bigger tool or machine and it's some sort of adjustment device. Hard to tell in the pics but are the threads standard or acme ?

Good question, standard 7/16-14 threads.

Looks like it pulls or stretches something.

spring installer,
prestretch the spring