diff --git a/support/doc/api/openapi.yaml b/support/doc/api/openapi.yaml
index ae4855878..6c5a15087 100644
--- a/support/doc/api/openapi.yaml
+++ b/support/doc/api/openapi.yaml
@@ -960,6 +960,12 @@ paths:
             Disambiguate via `type`:
             - `invalid_client` for an unmatched `client_id`
             - `invalid_grant` for unmatched credentials
+        '401':
+          x-summary: token expired
+          description: |
+            Disambiguate via `type`:
+            - default value for a regular authentication failure
+            - `invalid_token` for an expired token
       x-codeSamples:
         - lang: Shell
           source: |