diff --git a/core/lib/Drupal/Core/Entity/EntityFormBuilderInterface.php b/core/lib/Drupal/Core/Entity/EntityFormBuilderInterface.php
index 3549f4c..d89fec6 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormBuilderInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormBuilderInterface.php
@@ -9,12 +9,21 @@
 
 /**
  * Builds entity forms.
+ *
+ * This is like \Drupal\Core\Form\FormBuilderInterface but instead of supplying
+ * the form class directly it looks up the class based on an entity and an
+ * operation.
  */
 interface EntityFormBuilderInterface {
 
   /**
    * Gets the built and processed entity form for the given entity.
    *
+   * The form may also be retrieved from the cache if the form was built in a
+   * previous page-load. The form is then passed on for processing, validation
+   * and submission if there is proper input.
+   *
+   *
    * @param \Drupal\Core\Entity\EntityInterface $entity
    *   The entity to be created or edited.
    * @param string $operation
@@ -23,7 +32,17 @@
    *   @code
    *   _entity_form: node.book_outline
    *   @endcode
-   *   where "book_outline" is the value of $operation.
+   *   where "book_outline" is the value of $operation. The relevant class can
+   *   be found in the annotation of the entity under the form handlers, the
+   *   $operation is the key, the value is the class defined there. For
+   *   example:
+   *   @code
+   *   handlers = {
+   *     "storage" = "Drupal\node\NodeStorage",
+   *     "form" = {
+   *       "delete" = "Drupal\node\Form\NodeDeleteForm",
+   *   @endcode
+   *   Alternatively, the form class can be set from hook_entity_type_build().
    * @param array $form_state_additions
    *   (optional) An associative array used to build the current state of the
    *   form. Use this to pass additional information to the form, such as the
@@ -36,6 +55,10 @@
    *
    * @return array
    *   The processed form for the given entity and operation.
+   *
+   * @see \Drupal\Core\Form\FormBuilderInterface::getForm()
+   * @see \Drupal\Core\Entity\EntityTypeInterface::getFormClass()
+   * @see \Drupal\Core\Entity\EntityTypeInterface::setFormClass()
    */
   public function getForm(EntityInterface $entity, $operation = 'default', array $form_state_additions = array());