diff --git a/core/lib/Drupal/Core/Render/Annotation/FormElement.php b/core/lib/Drupal/Core/Render/Annotation/FormElement.php
index 8da7f53..b7288a0 100644
--- a/core/lib/Drupal/Core/Render/Annotation/FormElement.php
+++ b/core/lib/Drupal/Core/Render/Annotation/FormElement.php
@@ -8,7 +8,21 @@
 namespace Drupal\Core\Render\Annotation;
 
 /**
- * @todo.
+ * Defines a form element plugin annotation object.
+ *
+ * Form elements are also valid render elements, but they specifically represent
+ * an HTML element that takes input as part of a form. It will be discovered via
+ * the same mechanism as regular render element plugins.
+ *
+ * Plugin Namespace: Element
+ *
+ * For a working example, see \Drupal\Core\Render\Element\Textfield.
+ *
+ * @see \Drupal\Core\Render\ElementInfoManager
+ * @see \Drupal\Core\Render\ElementInterface
+ * @see \Drupal\Core\Render\FormElement
+ *
+ * @ingroup plugin_api
  *
  * @Annotation
  */
diff --git a/core/lib/Drupal/Core/Render/Annotation/RenderElement.php b/core/lib/Drupal/Core/Render/Annotation/RenderElement.php
index f7b5b03..cb03875 100644
--- a/core/lib/Drupal/Core/Render/Annotation/RenderElement.php
+++ b/core/lib/Drupal/Core/Render/Annotation/RenderElement.php
@@ -15,19 +15,19 @@
  * Render element plugins allow modules to declare their own Render API element
  * types and specify their default values.
  *
- * This hook allows modules to declare their own render element types and to
- * specify their default values. The values returned by this hook will be
+ * This annotation allows modules to declare their own render element types and
+ * to specify their default values. The values returned by this plugin will be
  * merged with the elements returned by render arrays and so can return defaults
  * for any Render APIs keys in addition to those explicitly documented by
  * \Drupal\Core\Render\ElementInfoManagerInterface::getInfo().
  *
  * Plugin Namespace: Element
  *
- * For a working example, see \Drupal\Core\Render\Element\Textfield.
+ * For a working example, see \Drupal\Core\Render\Element\Link.
  *
  * @see \Drupal\Core\Render\ElementInfoManager
- * @see \Drupal\Core\Render\ElementInfoPluginInterface
- * @see \Drupal\Core\Render\ElementInfoPluginBase
+ * @see \Drupal\Core\Render\ElementInterface
+ * @see \Drupal\Core\Render\RenderElement
  *
  * @ingroup plugin_api
  *
diff --git a/core/lib/Drupal/Core/Render/Element/ElementInterface.php b/core/lib/Drupal/Core/Render/Element/ElementInterface.php
index 7eb753a..020e18a 100644
--- a/core/lib/Drupal/Core/Render/Element/ElementInterface.php
+++ b/core/lib/Drupal/Core/Render/Element/ElementInterface.php
@@ -12,9 +12,11 @@
 /**
  * Provides an interface for element plugins.
  *
- * @see \Drupal\Core\Render\Annotation\ElementInfo
  * @see \Drupal\Core\Render\ElementInfoManager
- * @see \Drupal\Core\Render\ElementInfoBase
+ * @see \Drupal\Core\Render\Annotation\RenderElement
+ * @see \Drupal\Core\Render\Annotation\FormElement
+ * @see \Drupal\Core\Render\RenderElement
+ * @see \Drupal\Core\Render\FormElement
  */
 interface ElementInterface extends PluginInspectionInterface {
 
diff --git a/core/lib/Drupal/Core/Render/Element/FormElement.php b/core/lib/Drupal/Core/Render/Element/FormElement.php
index d3ee790..a118f0a 100644
--- a/core/lib/Drupal/Core/Render/Element/FormElement.php
+++ b/core/lib/Drupal/Core/Render/Element/FormElement.php
@@ -8,7 +8,13 @@
 namespace Drupal\Core\Render\Element;
 
 /**
- * @todo.
+ * Provides a base class for form render plugins.
+ *
+ * @see \Drupal\Core\Render\Annotation\FormElement
+ * @see \Drupal\Core\Render\ElementInterface
+ * @see \Drupal\Core\Render\ElementInfoManager
+ *
+ * @ingroup plugin_api
  */
 abstract class FormElement extends RenderElement {
 
diff --git a/core/lib/Drupal/Core/Render/Element/RenderElement.php b/core/lib/Drupal/Core/Render/Element/RenderElement.php
index cf6ad20..19cb772 100644
--- a/core/lib/Drupal/Core/Render/Element/RenderElement.php
+++ b/core/lib/Drupal/Core/Render/Element/RenderElement.php
@@ -11,10 +11,10 @@
 use Drupal\Core\Render\Element;
 
 /**
- * Provides a base class for element plugins.
+ * Provides a base class for element render plugins.
  *
- * @see \Drupal\Core\Render\Annotation\ElementInfo
- * @see \Drupal\Core\Render\ElementInfoInterface
+ * @see \Drupal\Core\Render\Annotation\RenderElement
+ * @see \Drupal\Core\Render\ElementInterface
  * @see \Drupal\Core\Render\ElementInfoManager
  *
  * @ingroup plugin_api
diff --git a/core/lib/Drupal/Core/Render/ElementInfoManager.php b/core/lib/Drupal/Core/Render/ElementInfoManager.php
index 43d0b86..a60e54d 100644
--- a/core/lib/Drupal/Core/Render/ElementInfoManager.php
+++ b/core/lib/Drupal/Core/Render/ElementInfoManager.php
@@ -14,9 +14,11 @@
 /**
  * Provides a plugin manager for element plugins.
  *
- * @see \Drupal\Core\Render\Annotation\ElementInfo
- * @see \Drupal\Core\Render\ElementInfoInterface
- * @see \Drupal\Core\Render\ElementInfoBase
+ * @see \Drupal\Core\Render\ElementInterface
+ * @see \Drupal\Core\Render\Annotation\RenderElement
+ * @see \Drupal\Core\Render\Annotation\FormElement
+ * @see \Drupal\Core\Render\RenderElement
+ * @see \Drupal\Core\Render\FormElement
  *
  * @ingroup plugin_api
  */
@@ -57,7 +59,8 @@ public function getInfo($type) {
    * Builds up all element information.
    */
   protected function buildInfo() {
-    // @todo Remove this hook once all elements are converted to plugins.
+    // @todo Remove this hook once all elements are converted to plugins in
+    //   https://www.drupal.org/node/2311393.
     $info = $this->moduleHandler->invokeAll('element_info');
 
     foreach ($this->getDefinitions() as $element_type => $definition) {
diff --git a/core/lib/Drupal/Core/Render/Plugin/README.txt b/core/lib/Drupal/Core/Render/Plugin/README.txt
index 7f04b88..f761e01 100644
--- a/core/lib/Drupal/Core/Render/Plugin/README.txt
+++ b/core/lib/Drupal/Core/Render/Plugin/README.txt
@@ -1,2 +1,4 @@
-@todo This must be here because DrupalKernel is stupid. Fix in
-  https://www.drupal.org/node/2309889.
+@todo This must be here because DrupalKernel will only allow namespaces to
+  provide plugins if there is a Plugin subdirectory, and git does not allow
+  empty subdirectories. This file should be removed once
+  https://www.drupal.org/node/2309889 is fixed.