diff --git a/openapi.yaml b/openapi.yaml
index 77d0e2318..fddfa8fdd 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -2347,7 +2347,12 @@ components:
           description: Device type (cuda, mps, cpu, etc.)
         index:
           type: number
-          description: Device index
+          nullable: true
+          description: |
+            Device index within its type (e.g. CUDA ordinal for `cuda:0`,
+            `cuda:1`). `null` for devices with no index, including the CPU
+            device returned in `--cpu` mode (PyTorch's `torch.device('cpu').index`
+            is `None`).
         vram_total:
           type: number
           description: Total VRAM in bytes
@@ -2503,7 +2508,11 @@ components:
           description: Alternative search terms for finding this node
         essentials_category:
           type: string
-          description: Category override used by the essentials pack
+          nullable: true
+          description: |
+            Category override used by the essentials pack. `null` for nodes
+            that don't set `ESSENTIALS_CATEGORY` (V1) or whose `Schema`
+            doesn't populate `essentials_category` (V3 / `comfy_api.latest.io`).
 
     # -------------------------------------------------------------------
     # Models