Callbacks service docs updated

interface/api/response/error.yaml

@@ -1,6 +1,7 @@
 components:
   schemas:
     ApiError:
+      description: Standard API error envelope with optional debugging details.
       type: object
       additionalProperties: false
       required:
@@ -9,11 +10,15 @@ components:
         - source
       properties:
         code:
+          description: Application-specific numeric error code.
           type: integer
           format: int32
         error:
+          description: Human-readable error summary.
           type: string
         source:
+          description: Component or subsystem that produced the error.
           type: string
         details:
+          description: Optional detailed message providing additional failure context.
           type: string