diff --git a/src/api/index.md b/src/api/index.md
index 6986f37c6a..5ae99bd9b3 100644
--- a/src/api/index.md
+++ b/src/api/index.md
@@ -424,7 +424,9 @@ type: api
       // type check plus other validations
       name: {
         type: String,
-        required: true
+        required: true,
+        // warn if not two way bound
+        twoWay: true
       }
     }
   })