Using hydra-eval-jobs to run all tests, evaluate nixpkgs

I couldn’t find any documentation on how to use hydra-eval-jobs program from hydra.
It was suggested to me as a way to run a very memory-intensive build/evaluation without triggering an OOM.

Running

$ nix-shell -p hydra --run 'hydra-eval-jobs -I . nixos/release.nix'

I get this error:

error: access to path '/nix/store/8ax3qd5bb5brbxa5wb7dc3nxmhgxgjng-nixpkgs' is forbidden in restricted mode

Has anyone here used it before? What am I doing wrong?