diff --git a/specification/ai/Azure.AI.Projects/evaluations/models.tsp b/specification/ai/Azure.AI.Projects/evaluations/models.tsp
index 990f9fc35093..f72bf164ab54 100644
--- a/specification/ai/Azure.AI.Projects/evaluations/models.tsp
+++ b/specification/ai/Azure.AI.Projects/evaluations/models.tsp
@@ -120,8 +120,8 @@ model AgentEvaluationRequest {
   @doc("Redaction configuration for the evaluation.")
   redactionConfiguration?: AgentEvaluationRedactionConfiguration;
 
-  @doc("Optional and temporary way to pass the AppInsights connection string to the evaluator. When this string is not null, the evaluation results will be logged to Azure AppInsights.")
-  appInsightsConnectionString?: string;
+  @doc("Pass the AppInsights connection string to the agent evaluation for the evaluation results and the errors logs.")
+  appInsightsConnectionString: string;
 }
 
 @doc("Result for the agent evaluation evaluator run.")
@@ -166,6 +166,9 @@ model AgentEvaluation {
   @doc("Status of the agent evaluation. Options: Running, Completed, Failed.")
   status: string;
 
+  @doc("The reason of the request failure for the long running process, if applicable.")
+  error?: string;
+
   @doc("The agent evaluation result.")
   result?: Array<AgentEvaluationResult>;
 }
diff --git a/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects-1dp.json b/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects-1dp.json
index 5f4a16d2309c..bd7eac5443e3 100644
--- a/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects-1dp.json
+++ b/specification/ai/data-plane/Azure.AI.Projects/preview/2025-05-15-preview/azure-ai-projects-1dp.json
@@ -1492,6 +1492,10 @@
           "type": "string",
           "description": "Status of the agent evaluation. Options: Running, Completed, Failed."
         },
+        "error": {
+          "type": "string",
+          "description": "The reason of the request failure for the long running process, if applicable."
+        },
         "result": {
           "type": "array",
           "description": "The agent evaluation result.",
@@ -1545,12 +1549,13 @@
         },
         "appInsightsConnectionString": {
           "type": "string",
-          "description": "Optional and temporary way to pass the AppInsights connection string to the evaluator. When this string is not null, the evaluation results will be logged to Azure AppInsights."
+          "description": "Pass the AppInsights connection string to the agent evaluation for the evaluation results and the errors logs."
         }
       },
       "required": [
         "runId",
-        "evaluators"
+        "evaluators",
+        "appInsightsConnectionString"
       ]
     },
     "AgentEvaluationResult": {