diff --git a/output/schema/schema.json b/output/schema/schema.json
index 4ce31fb384..8f96141020 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -58476,8 +58476,15 @@
       },
       "properties": [
         {
+          "availability": {
+            "serverless": {},
+            "stack": {
+              "since": "8.18.0"
+            }
+          },
+          "description": "Model ID is required for all dense_vector fields but\nmay be inferred for semantic_text fields",
           "name": "model_id",
-          "required": true,
+          "required": false,
           "type": {
             "kind": "instance_of",
             "type": {
@@ -58498,7 +58505,7 @@
           }
         }
       ],
-      "specLocation": "_types/Knn.ts#L94-L97"
+      "specLocation": "_types/Knn.ts#L94-L103"
     },
     {
       "kind": "interface",
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index d1fe73230b..522205083e 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -3015,7 +3015,7 @@ export interface TaskFailure {
 export type TaskId = string
 
 export interface TextEmbedding {
-  model_id: string
+  model_id?: string
   model_text: string
 }
 
diff --git a/specification/_types/Knn.ts b/specification/_types/Knn.ts
index 26c1967388..f5fef4666a 100644
--- a/specification/_types/Knn.ts
+++ b/specification/_types/Knn.ts
@@ -92,6 +92,12 @@ export interface QueryVectorBuilder {
 }
 
 export interface TextEmbedding {
-  model_id: string
+  /**
+   * Model ID is required for all dense_vector fields but
+   * may be inferred for semantic_text fields
+   * @availability stack since=8.18.0
+   * @availability serverless
+   */
+  model_id?: string
   model_text: string
 }