diff --git a/config/schema/insert.schema.yml b/config/schema/insert.schema.yml
index 609c855..64183cd 100644
--- a/config/schema/insert.schema.yml
+++ b/config/schema/insert.schema.yml
@@ -56,3 +56,30 @@ insert.config:
           label: 'Video file extensions'
           sequence:
             type: string
+
+field.widget.third_party.insert:
+  type: mapping
+  label: 'Insert module settings of field widgets'
+  mapping:
+    styles:
+      type: sequence
+      sequence:
+        type: string
+    default:
+      type: string
+    auto_image_style:
+      type: string
+    link_image:
+      type: string
+      nullable: true
+    caption:
+      type: boolean
+    width:
+      type: string
+    align:
+      type: boolean
+    rotate:
+      type: boolean
+    # Only appears in migration.
+    class:
+      type: string