Yes, there are clinical social workers in Mosaic, however to be included in the table the social worker must have submitted more than 10 professional Medicare claims in the most recent year.
At this time there is no way to distinguish by credentials (ie LCSW)
Find social workers by using the Specialty filter on the Explore page.
Make sure that you are on the Physicians tab.
Open the Specialty filter by clicking on it.
Type in "social."
Click on the entry "Social Worker."
Click on the filter button again to close the filter
The Explore table will then contain social workers, see image below