This is for creating, reading, and destroying arbitrary objects (blobs) in the git filesystem. These objects are not part of any branch or "working tree".
Example:
% echo hello | git rest put greeting
% git rest get greeting
hello
% git rest delete greeting
% git rest get greeting
fatal: Not a valid object name greeting
As git-rest's tags are not part of any tree, you will need to ask for them if you want to come along in a git-fetch like so:
% git fetch --tags
Better yet, tell git that you always want these kinds of tags:
% git config remote.<REMOTENAME>.tagopt --tags
% git fetch
If you use homebrew:
% brew tap drench/moregit
% brew install git-rest
Otherwise, put git-rest somewhere in your $PATH. May I suggest ~/bin/?