diff --git a/spec/paths/bookings.yaml b/spec/paths/bookings.yaml
index 3b7fae1..16bc88b 100644
--- a/spec/paths/bookings.yaml
+++ b/spec/paths/bookings.yaml
@@ -6,7 +6,9 @@ paths:
   /{version}/bookings:
     post:
       operationId: BookingsCreate
-      description: A booking request can create a shopping cart or add to an existing shopping cart. Either coupon or bookable must be sent in the body of the request.
+      description: |
+        A booking request can create a shopping cart or add to an existing shopping cart. Either coupon or bookable must be sent in the body of the request.
+        When `bookable` is sent, `option_id`, `datetime`, `price` and `categories` are required. A request that omits `bookable.price` is rejected with a `400`.
       summary: Create a new booking.
       tags:
         - Bookings