diff --git a/openapi/openapiv2.json b/openapi/openapiv2.json
index a6530b15..c561195f 100644
--- a/openapi/openapiv2.json
+++ b/openapi/openapiv2.json
@@ -8511,6 +8511,10 @@
         "operationId": {
           "type": "string",
           "description": "The operation ID returned by the Nexus handler in the response to the StartOperation request.\nThis ID is used when canceling the operation."
+        },
+        "requestId": {
+          "type": "string",
+          "description": "The request ID allocated at schedule time."
         }
       },
       "description": "Event marking an asynchronous operation was started by the responding Nexus handler.\nIf the operation completes synchronously, this event is not generated.\nIn rare situations, such as request timeouts, the service may fail to record the actual start time and will fabricate\nthis event upon receiving the operation completion via callback."
diff --git a/openapi/openapiv3.yaml b/openapi/openapiv3.yaml
index 803926a9..6c78015e 100644
--- a/openapi/openapiv3.yaml
+++ b/openapi/openapiv3.yaml
@@ -6271,6 +6271,9 @@ components:
           description: |-
             The operation ID returned by the Nexus handler in the response to the StartOperation request.
              This ID is used when canceling the operation.
+        requestId:
+          type: string
+          description: The request ID allocated at schedule time.
       description: |-
         Event marking an asynchronous operation was started by the responding Nexus handler.
          If the operation completes synchronously, this event is not generated.
diff --git a/temporal/api/history/v1/message.proto b/temporal/api/history/v1/message.proto
index 6dd0bc25..174d0869 100644
--- a/temporal/api/history/v1/message.proto
+++ b/temporal/api/history/v1/message.proto
@@ -839,6 +839,9 @@ message NexusOperationStartedEventAttributes {
     // The operation ID returned by the Nexus handler in the response to the StartOperation request.
     // This ID is used when canceling the operation.
     string operation_id = 3;
+
+    // The request ID allocated at schedule time.
+    string request_id = 4;
 }
 
 // Nexus operation completed successfully.