diff --git a/specification/_global/reindex_rethrottle/ReindexRethrottleRequest.ts b/specification/_global/reindex_rethrottle/ReindexRethrottleRequest.ts
index 46c8c31b17..710a0b7397 100644
--- a/specification/_global/reindex_rethrottle/ReindexRethrottleRequest.ts
+++ b/specification/_global/reindex_rethrottle/ReindexRethrottleRequest.ts
@@ -20,6 +20,7 @@
 import { RequestBase } from '@_types/Base'
 import { Id, MediaType } from '@_types/common'
 import { float } from '@_types/Numeric'
+import { GroupBy } from '@tasks/_types/GroupBy'
 
 /**
  * Throttle a reindex operation.
@@ -60,5 +61,9 @@ export interface Request extends RequestBase {
      * It can be either `-1` to turn off throttling or any decimal number like `1.7` or `12` to throttle to that level.
      */
     requests_per_second: float
+    /**
+     * @availability stack stability=stable
+     */
+    group_by?: GroupBy
   }
 }
diff --git a/specification/_global/reindex_rethrottle/ReindexRethrottleResponse.ts b/specification/_global/reindex_rethrottle/ReindexRethrottleResponse.ts
index 95837bea07..15635027a1 100644
--- a/specification/_global/reindex_rethrottle/ReindexRethrottleResponse.ts
+++ b/specification/_global/reindex_rethrottle/ReindexRethrottleResponse.ts
@@ -17,9 +17,15 @@
  * under the License.
  */
 
+import { ErrorCause, TaskFailure } from '@_types/Errors'
 import { Dictionary } from '@spec_utils/Dictionary'
-import { ReindexNode } from './types'
+import { ReindexNode, ReindexTasks } from './types'
 
 export class Response {
-  body: { nodes: Dictionary<string, ReindexNode> }
+  body: {
+    node_failures?: ErrorCause[]
+    task_failures?: TaskFailure[]
+    nodes?: Dictionary<string, ReindexNode>
+    tasks?: ReindexTasks
+  }
 }
diff --git a/specification/_global/reindex_rethrottle/types.ts b/specification/_global/reindex_rethrottle/types.ts
index 7069dd0edb..8fb35c5117 100644
--- a/specification/_global/reindex_rethrottle/types.ts
+++ b/specification/_global/reindex_rethrottle/types.ts
@@ -41,3 +41,12 @@ export class ReindexTask {
   type: string
   headers: HttpHeaders
 }
+
+/**
+ * @codegen_names flat, grouped
+ */
+export type ReindexTasks = ReindexTask[] | Dictionary<string, ParentReindexTask>
+
+export class ParentReindexTask extends ReindexTask {
+  children?: ReindexTask[]
+}