diff --git a/specification/cognitiveservices/AnomalyDetector/multivariate/models.cadl b/specification/cognitiveservices/AnomalyDetector/multivariate/models.cadl
index 0af8d1ade04b..7eb7859505b7 100644
--- a/specification/cognitiveservices/AnomalyDetector/multivariate/models.cadl
+++ b/specification/cognitiveservices/AnomalyDetector/multivariate/models.cadl
@@ -358,7 +358,7 @@ An optional field, which is used to specify the number of top contributed
 variables for one anomalous timestamp in the response. The default number is
 10.
 """)
-  topContributorCount: int32;
+  topContributorCount?: int32 = 10;
 }
 
 @doc("Variable values.")
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 3834617a2cc8..ba960917ae74 100644
--- a/specification/cognitiveservices/data-plane/AnomalyDetector/stable/v1.1/openapi.json
+++ b/specification/cognitiveservices/data-plane/AnomalyDetector/stable/v1.1/openapi.json
@@ -578,7 +578,8 @@
         "modelId": {
           "type": "string",
           "description": "Model identifier.",
-          "format": "uuid"
+          "format": "uuid",
+          "readOnly": true
         },
         "createdTime": {
           "type": "string",
@@ -1048,7 +1049,8 @@
         "resultId": {
           "type": "string",
           "description": "Result identifier, which is used to fetch the results of an inference call.",
-          "format": "uuid"
+          "format": "uuid",
+          "readOnly": true
         },
         "summary": {
           "$ref": "#/definitions/Multivariate.MultivariateBatchDetectionResultSummary",
@@ -1086,13 +1088,13 @@
         "topContributorCount": {
           "type": "integer",
           "format": "int32",
-          "description": "An optional field, which is used to specify the number of top contributed\nvariables for one anomalous timestamp in the response. The default number is\n10."
+          "description": "An optional field, which is used to specify the number of top contributed\nvariables for one anomalous timestamp in the response. The default number is\n10.",
+          "default": 10
         }
       },
       "description": "Request of last detection.",
       "required": [
-        "variables",
-        "topContributorCount"
+        "variables"
       ]
     },
     "Multivariate.MultivariateLastDetectionResult": {