Hi,
There’s no documented way to get stories/comments while querying the tasks. Stories aren’t listed as a sub field in the data model for Tasks, and requesting opt_expand=stories doesn’t do anything.
Interestingly opt_expand=subtasks does work for now, but this is undocumented and Asana would rather you use opt_fields=num_subtasks to determine if you should look them up.
Unfortunately there’s no equivalent num_stories or num_comments field, and every task is likely to have at least one story when it is first added to a project. So, to find all the comments, you’ll have to query the /stories endpoint for every task.
This is what I have implemented for Ditto, so if there’s a faster way I’d be interested in knowing!