diff --git a/core/lib/Drupal/Core/TypedData/ListInterface.php b/core/lib/Drupal/Core/TypedData/ListInterface.php
index 6a83721..6c6e5c3 100644
--- a/core/lib/Drupal/Core/TypedData/ListInterface.php
+++ b/core/lib/Drupal/Core/TypedData/ListInterface.php
@@ -50,8 +50,9 @@ public function onChange($delta);
    * @param int $index
    *   Index of the item to return.
    *
-   * @return
-   *   The item at the specified position in this list.
+   * @return \Drupal\Core\TypedData\TypedDataInterface
+   *   The item at the specified position in this list. An empty item is created
+   *   if it does not exist yet.
    */
   public function get($index);
 
@@ -62,13 +63,16 @@ public function get($index);
    *   Index of the item to replace.
    * @param mixed
    *   Item to be stored at the specified position.
+   *
+   * @return self
+   *   Returns the list.
    */
   public function set($index, $item);
 
   /**
    * Returns the first item in this list.
    *
-   * @return
+   * @return \Drupal\Core\TypedData\TypedDataInterface
    *   The first item in this list.
    */
   public function first();