diff --git a/data/api/client-server/administrative_contact.yaml b/data/api/client-server/administrative_contact.yaml
index eddb2b01..2ce11e53 100644
--- a/data/api/client-server/administrative_contact.yaml
+++ b/data/api/client-server/administrative_contact.yaml
@@ -120,6 +120,7 @@ paths:
                       description: The client secret used in the session with the identity server.
                     id_server:
                       type: string
+                      format: mx-server-name
                       description: The identity server to use.
                     id_access_token:
                       type: string
@@ -279,6 +280,7 @@ paths:
                   description: The client secret used in the session with the identity server.
                 id_server:
                   type: string
+                  format: mx-server-name
                   description: The identity server to use.
                 id_access_token:
                   type: string
@@ -338,6 +340,7 @@ paths:
               properties:
                 id_server:
                   type: string
+                  format: mx-server-name
                   description: |-
                     The identity server to unbind from. If not provided, the homeserver
                     MUST use the `id_server` the identifier was added through. If the
@@ -408,6 +411,7 @@ paths:
               properties:
                 id_server:
                   type: string
+                  format: mx-server-name
                   description: |-
                     The identity server to unbind from. If not provided, the homeserver
                     MUST use the `id_server` the identifier was added through. If the