Answer Question
Tree of Work Items returns more items than query defines
There seems to be a bug where Tree of Work Items) brings in all work items in the tree regardless of the query you select. I would expect Work Items and Directly Links to do that, but not Tree of Work Items.
For example, we have a query that brings back Features and Product Backlog Items, and we use the Get WorkItem and the result type of Tree of Work Items, we get all the tasks associated with the Product Backlog Items inserted into the document as well.