diff --git a/specification/cognitiveservices/AnomalyDetector/multivariate/models.tsp b/specification/cognitiveservices/AnomalyDetector/multivariate/models.tsp
index 1618555e8386..f69f05a364a1 100644
--- a/specification/cognitiveservices/AnomalyDetector/multivariate/models.tsp
+++ b/specification/cognitiveservices/AnomalyDetector/multivariate/models.tsp
@@ -129,11 +129,9 @@ to be detected.
   dataSource: url;
 
   @doc("""
-Number of top contributed
-variables for one anomalous time stamp in the response. The default is
-10.
+Number of top contributed variables for one anomalous time stamp in the response.
 """)
-  topContributorCount: int32;
+  topContributorCount?: int32 = 10;
 
   @doc("""
 Start date/time of data for detection, which should
diff --git a/specification/cognitiveservices/data-plane/AnomalyDetector/stable/v1.1/openapi.json b/specification/cognitiveservices/data-plane/AnomalyDetector/stable/v1.1/openapi.json
index 202c6b6a509c..4b1365f8fd47 100644
--- a/specification/cognitiveservices/data-plane/AnomalyDetector/stable/v1.1/openapi.json
+++ b/specification/cognitiveservices/data-plane/AnomalyDetector/stable/v1.1/openapi.json
@@ -936,7 +936,8 @@
         "topContributorCount": {
           "type": "integer",
           "format": "int32",
-          "description": "Number of top contributed\nvariables for one anomalous time stamp in the response. The default is\n10."
+          "description": "Number of top contributed variables for one anomalous time stamp in the response.",
+          "default": 10
         },
         "startTime": {
           "type": "string",
@@ -952,7 +953,6 @@
       "description": "Detection request for batch inference. This is an asynchronous inference that\nwill need another API to get detection results.",
       "required": [
         "dataSource",
-        "topContributorCount",
         "startTime",
         "endTime"
       ]