diff --git a/mmv1/products/ces/Tool.yaml b/mmv1/products/ces/Tool.yaml
index cf3ce15f65fd..5a2ec05277b7 100644
--- a/mmv1/products/ces/Tool.yaml
+++ b/mmv1/products/ces/Tool.yaml
@@ -579,7 +579,6 @@ properties:
               Full resource name of the Engine.
               Format:
               `projects/{project}/locations/{location}/collections/{collection}/engines/{engine}`
-            required: true
           - name: filter
             type: String
             description: |-