diff --git a/wp-includes/capabilities.php b/wp-includes/capabilities.php
index c192639608..7fd4a0a29f 100644
--- a/wp-includes/capabilities.php
+++ b/wp-includes/capabilities.php
@@ -705,10 +705,23 @@ function author_can( $post, $capability ) {
 /**
  * Whether a particular user has a specific capability.
  *
+ * While checking against particular roles in place of a capability is supported
+ * in part, this practice is discouraged as it may produce unreliable results.
+ *
+ * Note: Will always return true if the current user is a super admin, unless specifically denied.
+ *
  * @since 3.1.0
  *
+ * @see WP_User::has_cap()
+ * @see map_meta_cap()
+ *
  * @param int|WP_User $user       User ID or object.
  * @param string      $capability Capability name.
+ * @param int         $object_id  Optional. ID of the specific object to check against if `$capability` is a "meta" cap.
+ *                                "Meta" capabilities, e.g. 'edit_post', 'edit_user', etc., are capabilities used
+ *                                by map_meta_cap() to map to other "primitive" capabilities, e.g. 'edit_posts',
+ *                                'edit_others_posts', etc. Accessed via func_get_args() and passed to WP_User::has_cap(),
+ *                                then map_meta_cap().
  * @return bool Whether the user has the given capability.
  */
 function user_can( $user, $capability ) {