diff --git a/core/lib/Drupal/Core/Render/Element/Checkboxes.php b/core/lib/Drupal/Core/Render/Element/Checkboxes.php
index 8d6919821f1..e767693046a 100644
--- a/core/lib/Drupal/Core/Render/Element/Checkboxes.php
+++ b/core/lib/Drupal/Core/Render/Element/Checkboxes.php
@@ -23,6 +23,12 @@ use Drupal\Core\Form\FormStateInterface;
  * );
  * @endcode
  *
+ * Element properties may be set on single option items as follows.
+ *
+ * @code
+ * $form['high_school']['tests_taken']['SAT']['#description'] = $this->t('Description for the SAT option.');
+ * @endcode
+ *
  * @see \Drupal\Core\Render\Element\Radios
  * @see \Drupal\Core\Render\Element\Checkbox
  *
diff --git a/core/lib/Drupal/Core/Render/Element/Radios.php b/core/lib/Drupal/Core/Render/Element/Radios.php
index 38a043e5f91..ab33869cd90 100644
--- a/core/lib/Drupal/Core/Render/Element/Radios.php
+++ b/core/lib/Drupal/Core/Render/Element/Radios.php
@@ -22,6 +22,12 @@ use Drupal\Component\Utility\Html as HtmlUtility;
  * );
  * @endcode
  *
+ * Element properties may be set on single option items as follows.
+ *
+ * @code
+ * $form['settings']['active'][0]['#description'] = $this->t('Description for the Closed option.');
+ * @endcode
+ *
  * @see \Drupal\Core\Render\Element\Checkboxes
  * @see \Drupal\Core\Render\Element\Radio
  * @see \Drupal\Core\Render\Element\Select