diff --git a/extensions/bootstrap/Collapse.php b/extensions/bootstrap/Collapse.php
index a71c23d8abc..80b97557139 100644
--- a/extensions/bootstrap/Collapse.php
+++ b/extensions/bootstrap/Collapse.php
@@ -86,6 +86,7 @@ public function run()
 
     /**
      * Renders collapsible items as specified on [[items]].
+     * @throws InvalidConfigException if label isn't specified
      * @return string the rendering result
      */
     public function renderItems()
diff --git a/extensions/debug/models/search/Mail.php b/extensions/debug/models/search/Mail.php
index 50d2c2c012a..f30076a802b 100644
--- a/extensions/debug/models/search/Mail.php
+++ b/extensions/debug/models/search/Mail.php
@@ -60,6 +60,9 @@ class Mail extends Base
     public $file;
 
 
+    /**
+     * @inheritdoc
+     */
     public function rules()
     {
         return [
diff --git a/extensions/redis/ActiveQuery.php b/extensions/redis/ActiveQuery.php
index 3a6248a8e83..702ce2d6459 100644
--- a/extensions/redis/ActiveQuery.php
+++ b/extensions/redis/ActiveQuery.php
@@ -305,6 +305,7 @@ public function scalar($attribute, $db = null)
      * If this parameter is not given, the `db` application component will be used.
      * @param string $type the type of the script to generate
      * @param string $columnName
+     * @throws NotSupportedException
      * @return array|bool|null|string
      */
     protected function executeScript($db, $type, $columnName = null)
diff --git a/extensions/twig/ViewRendererStaticClassProxy.php b/extensions/twig/ViewRendererStaticClassProxy.php
index 6ec612ebd80..facca46b6ed 100644
--- a/extensions/twig/ViewRendererStaticClassProxy.php
+++ b/extensions/twig/ViewRendererStaticClassProxy.php
@@ -18,11 +18,18 @@ class ViewRendererStaticClassProxy
     private $_staticClassName;
 
 
+    /**
+     * @param string $staticClassName
+     */
     public function __construct($staticClassName)
     {
         $this->_staticClassName = $staticClassName;
     }
 
+    /**
+     * @param string $property
+     * @return mixed
+     */
     public function __get($property)
     {
         $class = new \ReflectionClass($this->_staticClassName);
@@ -30,6 +37,11 @@ public function __get($property)
         return $class->getStaticPropertyValue($property);
     }
 
+    /**
+     * @param string $property
+     * @param mixed $value
+     * @return mixed
+     */
     public function __set($property, $value)
     {
         $class = new \ReflectionClass($this->_staticClassName);
@@ -38,6 +50,11 @@ public function __set($property, $value)
         return $value;
     }
 
+    /**
+     * @param string $method
+     * @param array $arguments
+     * @return mixed
+     */
     public function __call($method, $arguments)
     {
         return call_user_func_array([$this->_staticClassName, $method], $arguments);