How can I use standalone `tree-sitter parse` with existing language grammars?

I would like to test tree-sitter to parse python programs. I started by trying:

$ nix-shell -p tree-sitter --run "tree-sitter parse ast.py"
[...]
Warning: You have not configured any parser directories!
Please run `tree-sitter init-config` and edit the resulting
configuration file to indicate where we should look for
language grammars.

No language found

Seems that init-config would clutter my home. I hope there is a way to avoid that home-dependent plumbing in NixOS…

As far as I understand, we package common grammars, for example tree-sitter-grammars.tree-sitter-python.
Following nixpkgs/pkgs/development/tools/parsing/tree-sitter/default.nix at 50b3bd3fed0442bcbf7f58355e990da84af1749d · NixOS/nixpkgs · GitHub, I tried:

$ nix-shell -p "tree-sitter.withPlugins(ps: [ ps.tree-sitter-python ])" --run "tree-sitter parse atbdx2024/examples/ast.py"
[...]
/tmp/nix-shell-213097-0/rc: line 3: tree-sitter: command not found

Am I misunderstanding how withPlugins is supposed to work?

cc @Profpatsch