structuredAttrs is enabled

trying https://github.com/activeing123/mcptoon/archive/refs/tags/v0.5.4.tar.gz
  % Total    % Received % Xferd  Average Speed  Time    Time    Time   Current
                                 Dload  Upload  Total   Spent   Left   Speed

  0      0   0      0   0      0      0      0                              0
  0      0   0      0   0      0      0      0                              0
  0      0   0      0   0      0      0      0                              0

  0      0   0      0   0      0      0      0                              0
100 303.3k   0 303.3k   0      0 465.1k      0                              0
100 303.3k   0 303.3k   0      0 465.0k      0                              0
100 303.3k   0 303.3k   0      0 465.0k      0                              0
unpacking source archive /nix/var/nix/builds/nix-37992-3727977416/download.tar.gz