I don’t think a simple tool can interact with the editor, you may need to make a plugin and with the EditorPlugin use edit or edit_resource.
Another option that involves a lot less work would just be to create an EditorScript that gets the EditorInterface during the _run method and uses it to set the current scene in the editor. You can then easily run it by going to the ScriptEditor, opening the script, and hitting Ctrl+Shift+X to run it.