Q:

How do you include Azure Search's @search.score as part of your custom $orderby clause

According to this page, the default sort of Azure Search results is by Azure's own score (descending).  However, you can supply an $orderby clause, which is defined as:

A list of comma-separated expressions to sort the results by. Each
  expression can be either a field name or a call to the geo.distance()
  function.

I want to sort by Azure's @search.score desc, MyFieldOne, MyFieldTwo.  But, I cannot figure out how to reference the @search.score "field."
I've tried the following:
$orderby=search.score+desc,MyFieldOne,MyFieldTwo
$orderby=@search.score+desc,MyFieldOne,MyFieldTwo
$orderby=%40search.score+desc,MyFieldOne,MyFieldTwo

These all result in http 502 or 400s.
How do I reference the @search.score value in my request?

A:

Edited
Azure Search now supports sorting by score using the new search.score() OData function. For example, to sort by score then by name, do this:
$orderby=search.score() desc, name asc
The API reference has been updated to include the new search.score() function.
Original answer:
Azure Search currently doesn't let you refer to the score in an orderby clause. Please vote for this UserVoice suggestion to help us prioritize this work. 
Note, however, that score will rarely be the same for two documents, so using tie-breakers after the $oderby=@search.score will rarely come into play, and in most cases the sort order will be equivalent to sorting by rank, which is what happens by default.  

