diff --git a/specification/ml/start_trained_model_deployment/MlStartTrainedModelDeploymentRequest.ts b/specification/ml/start_trained_model_deployment/MlStartTrainedModelDeploymentRequest.ts
index 1b5e9803c6..c1fa2bba77 100644
--- a/specification/ml/start_trained_model_deployment/MlStartTrainedModelDeploymentRequest.ts
+++ b/specification/ml/start_trained_model_deployment/MlStartTrainedModelDeploymentRequest.ts
@@ -47,6 +47,11 @@ export interface Request extends RequestBase {
      * `0b` can be provided.
      */
     cache_size?: ByteSize
+    /**
+     * A unique identifier for the deployment of the model.
+     * @availability stack since=8.8.0
+     */
+    deployment_id?: string
     /**
      * The number of model allocations on each node where the model is deployed.
      * All allocations on a node share the same copy of the model in memory but use