diff --git a/core/lib/Drupal/Core/TypedData/DataDefinition.php b/core/lib/Drupal/Core/TypedData/DataDefinition.php
index 8ac57a164100e47470d8d8152fbcbca808cf1048..9653d09670a18d72668002ec30ee4fdf235e9267 100644
--- a/core/lib/Drupal/Core/TypedData/DataDefinition.php
+++ b/core/lib/Drupal/Core/TypedData/DataDefinition.php
@@ -78,7 +78,7 @@ public function getLabel() {
   /**
    * Sets the human-readable label.
    *
-   * @param string $label
+   * @param string|\Drupal\Core\StringTranslation\TranslatableMarkup $label
    *   The label to set.
    *
    * @return static
@@ -99,7 +99,7 @@ public function getDescription() {
   /**
    * Sets the human-readable description.
    *
-   * @param string $description
+   * @param string|\Drupal\Core\StringTranslation\TranslatableMarkup $description
    *   The description to set.
    *
    * @return static
diff --git a/core/lib/Drupal/Core/TypedData/DataDefinitionInterface.php b/core/lib/Drupal/Core/TypedData/DataDefinitionInterface.php
index a709b7a5c5239cc2ce8cfa499bddd4926d1d665d..e5614d3d462e85e092f7fad8a2f43654463b4a6f 100644
--- a/core/lib/Drupal/Core/TypedData/DataDefinitionInterface.php
+++ b/core/lib/Drupal/Core/TypedData/DataDefinitionInterface.php
@@ -57,9 +57,10 @@ public function getDataType();
   /**
    * Returns a human readable label.
    *
-   * @return string|\Drupal\Core\StringTranslation\TranslatableMarkup
+   * @return string|\Drupal\Core\StringTranslation\TranslatableMarkup|null
    *   The label. A string or an instance of TranslatableMarkup will be returned
-   *   based on the way the label translation is handled.
+   *   based on the way the label translation is handled. NULL if no label is
+   *   available.
    */
   public function getLabel();
 
@@ -69,8 +70,10 @@ public function getLabel();
    * Descriptions are usually used on user interfaces where the data is edited
    * or displayed.
    *
-   * @return string|null
-   *   The description, or NULL if no description is available.
+   * @return string|\Drupal\Core\StringTranslation\TranslatableMarkup|null
+   *   The description. A string or an instance of TranslatableMarkup will be
+   *   returned based on the way the description translation is handled. NULL if
+   *   no description is available.
    */
   public function getDescription();