How to add v1 when specifying the URL of an API?
All I had to do was to add another argument and clear the cache.

"args" =&gt; array(
   array(
     "name" =&gt; "version",
     "optional" =&gt; false,
     "source" =&gt; array("path" =&gt; 0),
     "type" =&gt; "string",
     "description" =&gt; "The API version."
   ),
   array(
     "name" =&gt; "id",
     "optional" =&gt; false,
     "source" =&gt; array("path" =&gt; 1),
     "type" =&gt; "int",
     "description" =&gt; "The id of the course to retrieve."
   )
),