Fetch topics sorted by Last post date for custom tags

Hi, 

We are using following API call to fetch all posts related to custom tag: 

/boards/id/${coreNodeId}/posts/for/metadata/key/modbar.${tagSearch}/value/true 

where, 
coreNode = board id, 
tagSearch = custom tag. 

Do we have any API call to get threads associated with a particular custom tag sorted by last post date. 

We tried using "message_viewer.topic_sort_order=last_post_date" parameter but it does not work for above call. 

Please let us know, if there is an API call which will satisfy above requirement. 

Thank you. 

Regards,

Vishwajeet