diff --git a/core/lib/Drupal/Core/Access/CustomAccessCheck.php b/core/lib/Drupal/Core/Access/CustomAccessCheck.php
index 20cd388..615ef97 100644
--- a/core/lib/Drupal/Core/Access/CustomAccessCheck.php
+++ b/core/lib/Drupal/Core/Access/CustomAccessCheck.php
@@ -13,6 +13,9 @@
 
 /**
  * Defines a access checker that allows to specify a custom function for access.
+ *
+ * You should only use it when you are sure that the access callback will not be
+ * reused. Good examples in core are edit or toolbar module.
  */
 class CustomAccessCheck implements StaticAccessCheckInterface {