Not sure if this is a bug or a feature request, but calckey can only be used while inside a git repository (though the specified file can be anywhere).

Can this be changed so it can be run from anywhere?

~$ git annex version
git-annex version: 6.20160613-g1e4e6f4

~$ git annex calckey /some/file/some/wh.ere
git-annex: Not in a git repository.
CallStack (from HasCallStack):
  error, called at ./Git/CurrentRepo.hs:55:37 in main:Git.CurrentRepo