diff --git a/core/modules/system/lib/Drupal/system/Annotation/MenuLocalTask.php b/core/modules/system/lib/Drupal/system/Annotation/MenuLocalTask.php
index 59e5e42..5fc8e7c 100644
--- a/core/modules/system/lib/Drupal/system/Annotation/MenuLocalTask.php
+++ b/core/modules/system/lib/Drupal/system/Annotation/MenuLocalTask.php
@@ -24,7 +24,7 @@ class MenuLocalTask extends Plugin {
   public $id;
 
   /**
-   * The static title for the local action.
+   * The static title for the local task.
    *
    * @ingroup plugin_translatable
    *
diff --git a/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskBase.php b/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskBase.php
index e12c47f..274f09b 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskBase.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskBase.php
@@ -54,8 +54,7 @@
    *   The url generator object.
    */
   public function __construct(array $configuration, $plugin_id, array $plugin_definition, TranslatorInterface $string_translation, UrlGeneratorInterface $generator) {
-    // This is available for subclasses that need to translate
-    // a dynamic title.
+    // This is available for subclasses that need to translate a dynamic title.
     $this->t = $string_translation;
     $this->generator = $generator;
     parent::__construct($configuration, $plugin_id, $plugin_definition);
@@ -82,7 +81,10 @@ public function getRouteName() {
   }
 
   /**
-   * {@inheritdoc}
+   * Returns the localized title to be shown for this tab.
+   *
+   * Subclasses may add arguments for request attributes which will then be
+   * automatically supplied by the controller resolver.
    */
   public function getTitle() {
     // Subclasses may pull in the request or specific attributes as parameters.
@@ -90,15 +92,17 @@ public function getTitle() {
   }
 
   /**
-   * {@inheritdoc}
+   * Returns an internal Drupal path to use when creating the link for the tab.
+   *
+   * Subclasses may add arguments for request attributes which will then be
+   * automatically supplied by the controller resolver.
    */
   public function getPath() {
-    // Subclasses may set a request into the generator or
-    // use any desired method to generate the path.
+    // Subclasses may set a request into the generator or use any desired method
+    // to generate the path.
     // @todo - use the new method from https://drupal.org/node/2031353
     $path = $this->generator->generate($this->getRouteName());
-    // In order to get the Drupal path the base URL has
-    // to be stripped off.
+    // In order to get the Drupal path the base URL has to be stripped off.
     $base_url = $this->generator->getContext()->getBaseUrl();
     if (!empty($base_url) && strpos($path, $base_url) === 0) {
       $path = substr($path, strlen($base_url));
@@ -144,6 +148,7 @@ public function getOptions() {
    */
   public function setActive($active = TRUE) {
     $this->active = $active;
+    return $this;
   }
 
   /**
diff --git a/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskInterface.php b/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskInterface.php
index ce564c5..0db9b1f 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskInterface.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/MenuLocalTaskInterface.php
@@ -8,7 +8,7 @@
 namespace Drupal\system\Plugin;
 
 /**
- * Defines an interface for menu local actions.
+ * Defines an interface for menu local tasks.
  */
 interface MenuLocalTaskInterface {
 
@@ -16,30 +16,14 @@
    * Get the route name from the settings.
    *
    * @return string
-   *   The name of the route this action links to.
+   *   The name of the route this local task links to.
    */
   public function getRouteName();
 
   /**
-   * Returns the localized title to be shown for this tab.
-   *
-   * Subclasses may add optional arguments like NodeInterface $node = NULL that
-   * will be supplied by the ControllerResolver.
-   */
-  public function getTitle();
-
-  /**
-   * Returns an internal Drupal path to use when creating the link for the tab.
-   *
-   * Subclasses may add optional arguments like NodeInterface $node = NULL that
-   * will be supplied by the ControllerResolver.
-   */
-  public function getPath();
-
-  /**
    * Returns the weight of the local task.
    *
-   * @return int|NULL
+   * @return int|null
    *   The weight of the task or NULL.
    */
   public function getWeight();
@@ -59,6 +43,9 @@ public function getOptions();
    *
    * @param bool $active
    *   Sets whether this tab is active (e.g. a parent of the current tab).
+   *
+   * @return \Drupal\system\Plugin\MenuLocalTaskInterface
+   *   The called object for chaining.
    */
   public function setActive($active = TRUE);
 
@@ -66,7 +53,9 @@ public function setActive($active = TRUE);
    * Gets the active status.
    *
    * @return bool
-   *   TRUE or FALSE. Can be changed by calling setActive().
+   *   TRUE if the local task is active, FALSE otherwise.
+   *
+   * @see \Drupal\system\Plugin\MenuLocalTaskInterface::setActive()
    */
   public function getActive();
 
diff --git a/core/modules/system/lib/Drupal/system/Plugin/Type/MenuLocalTaskManager.php b/core/modules/system/lib/Drupal/system/Plugin/Type/MenuLocalTaskManager.php
index f7a42c1..6f3e247 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/Type/MenuLocalTaskManager.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/Type/MenuLocalTaskManager.php
@@ -18,9 +18,9 @@
 /**
  * Manages discovery and instantiation of menu local task plugins.
  *
- * This manager finds plugs the put a local task (usually a tab) on Drupal
- * pages. Derivatives are supported for modules that wish to generate
- * new tabs not in code.
+ * This manager finds plugins that are rendered as local tasks (usually tabs).
+ * Derivatives are supported for modules that wish to generate multiple tabs on
+ * behalf of something else.
  */
 class MenuLocalTaskManager extends DefaultPluginManager {
 
@@ -77,33 +77,36 @@ public function __construct(\Traversable $namespaces, ControllerResolverInterfac
    * Gets the title for a local task.
    *
    * @param \Drupal\system\Plugin\MenuLocalTaskInterface $local_task
-   *   An object to get the title from.
+   *   A local task plugin instance to get the title for.
    *
    * @return string
-   *   The title (already localized).
+   *   The localized title.
    */
   public function getTitle(MenuLocalTaskInterface $local_task) {
-
     $controller = array($local_task, 'getTitle');
-    $arguments = $this->controllerResolver->getArguments($this->request, $controller);
-
-    return call_user_func_array($controller, $arguments);
+    if (is_callable($controller)) {
+      $arguments = $this->controllerResolver->getArguments($this->request, $controller);
+      return call_user_func_array($controller, $arguments);
+    }
+    throw new \BadMethodCallException('Menu local task plugins must implement a getTitle() method.');
   }
 
   /**
    * Gets the Drupal path for a local task.
    *
    * @param \Drupal\system\Plugin\MenuLocalTaskInterface $local_task
-   *   An object to get the path from.
+   *   The local task plugin instance to get the path for.
    *
    * @return string
    *   The path.
    */
   public function getPath(MenuLocalTaskInterface $local_task) {
     $controller = array($local_task, 'getPath');
-    $arguments = $this->controllerResolver->getArguments($this->request, $controller);
-
-    return call_user_func_array($controller, $arguments);
+    if (is_callable($controller)) {
+      $arguments = $this->controllerResolver->getArguments($this->request, $controller);
+      return call_user_func_array($controller, $arguments);
+    }
+    throw new \BadMethodCallException('Menu local task plugins must implement a getPath() method.');
   }
 
   /**
@@ -115,7 +118,7 @@ public function getPath(MenuLocalTaskInterface $local_task) {
    * @return array
    *   Returns an array of task levels. Each task level contains instances
    *   of local tasks (MenuLocalTaskInterface) which appear on the tab route.
-   *   The array keys are the depth, and at each depth is an array of
+   *   The array keys are the depths and the values are arrays of plugin
    *   instances.
    */
   public function getLocalTasksForRoute($route_name) {
@@ -184,7 +187,7 @@ public function getLocalTasksForRoute($route_name) {
   }
 
   /**
-   * Get the render array for all local tasks.
+   * Gets the render array for all local tasks.
    *
    * @param string $route_name
    *   The route for which to make renderable local tasks.