diff --git a/src/Mailer.php b/src/Mailer.php
index c71f25c..805d351 100644
--- a/src/Mailer.php
+++ b/src/Mailer.php
@@ -16,6 +16,21 @@
 use function basename;
 use function mime_content_type;
 
+/**
+ * Provides a way to send email messages.
+ *
+ * ```php
+ * $mailer
+ *     ->attachments(['@resources/attachment/test.txt'])
+ *     ->from('admin@example.com')
+ *     ->layout(['html' => 'contact'])
+ *     ->signatureImage('@resources/attachment/test.txt')
+ *     ->signatureText('Signature')
+ *     ->subject('Test subject')
+ *     ->viewPath('@views')
+ *     ->send('test@example.com', ['message' => 'Test body', 'username' => 'Test username']);
+ * ```
+ */
 final class Mailer
 {
     /** @psalm-var string[] */
diff --git a/src/Parameter.php b/src/Parameter.php
index dc39aad..6cd97dc 100644
--- a/src/Parameter.php
+++ b/src/Parameter.php
@@ -4,9 +4,14 @@
 
 namespace Yii\Service;
 
+use RuntimeException;
 use Yiisoft\Aliases\Aliases;
 use Yiisoft\Arrays\ArrayHelper;
 
+use function is_array;
+use function is_bool;
+use function is_string;
+
 /**
  * Parameter provides a way to get application Parameter defined in config/parameters.php.
  *
@@ -45,4 +50,21 @@ public function get(string $key, mixed $default = null): mixed
 
         return $value;
     }
+
+    public function getCastString(string $key, mixed $default = null): string
+    {
+        /** @psalm-var mixed $value */
+        $value = $this->get($key, $default);
+
+        if (is_array($value)) {
+            throw new RuntimeException(
+                'Unable to cast array to string. Please use `get()` method instead of `getCastString()`.'
+            );
+        }
+
+        return match (true) {
+            is_bool($value) => $value ? 'true' : 'false',
+            default => (string) $value,
+        };
+    }
 }
diff --git a/src/ParameterInterface.php b/src/ParameterInterface.php
index 73d8847..8dea97d 100644
--- a/src/ParameterInterface.php
+++ b/src/ParameterInterface.php
@@ -4,6 +4,9 @@
 
 namespace Yii\Service;
 
+/**
+ * Provides a way to get application Parameter defined in `config/application-params.php`.
+ */
 interface ParameterInterface
 {
     /**
@@ -15,4 +18,12 @@ interface ParameterInterface
      * @return mixed
      */
     public function get(string $key, mixed $default = null): mixed;
+
+    /**
+     * Returns a parameter defined in params as string.
+     *
+     * @param string $key The key of the parameter to return.
+     * @param mixed $default The default value to return if the parameter does not exist.
+     */
+    public function getCastString(string $key, mixed $default = null): string;
 }
diff --git a/src/Redirect.php b/src/Redirect.php
index 18e99f5..6ebcd7d 100644
--- a/src/Redirect.php
+++ b/src/Redirect.php
@@ -9,6 +9,13 @@
 use Psr\Http\Message\ResponseInterface;
 use Yiisoft\Router\UrlGeneratorInterface;
 
+/**
+ * Provides a way to redirect to a URL.
+ *
+ * ```php
+ * $response = $redirect->run('site/index');
+ * ```
+ */
 final class Redirect
 {
     public function __construct(
diff --git a/tests/Mailer/ImmutabilityTest.php b/tests/Mailer/ImmutabilityTest.php
index 2006966..1c918a3 100644
--- a/tests/Mailer/ImmutabilityTest.php
+++ b/tests/Mailer/ImmutabilityTest.php
@@ -13,8 +13,6 @@ final class ImmutabilityTest extends TestCase
 
     public function testImmutability(): void
     {
-        $this->createContainer();
-
         $mailer = $this->mailer;
 
         $this->assertNotSame($mailer, $mailer->attachments([]));
diff --git a/tests/Mailer/Test.php b/tests/Mailer/Test.php
index 459b412..b86bc7c 100644
--- a/tests/Mailer/Test.php
+++ b/tests/Mailer/Test.php
@@ -14,8 +14,6 @@ final class Test extends TestCase
 
     public function testMailer(): void
     {
-        $this->createContainer();
-
         $this->assertTrue(
             $this->mailer
                 ->attachments(['@resources/attachment/test.txt'])
@@ -49,8 +47,6 @@ public function testMailerFailed(): void
 
     public function testMailerWithEmptySignatureImage(): void
     {
-        $this->createContainer();
-
         $this->assertTrue(
             $this->mailer
                 ->attachments(['@resources/attachment/test.txt'])
@@ -66,8 +62,6 @@ public function testMailerWithEmptySignatureImage(): void
 
     public function testMailerWithTranslatorCategory(): void
     {
-        $this->createContainer();
-
         $this->assertTrue(
             $this->mailer
                 ->attachments(['@resources/attachment/test.txt'])
diff --git a/tests/Parameter/Test.php b/tests/Parameter/Test.php
index 3297b95..69d7d15 100644
--- a/tests/Parameter/Test.php
+++ b/tests/Parameter/Test.php
@@ -11,6 +11,33 @@ final class Test extends TestCase
 {
     use TestTrait;
 
+    public function testGetCastString(): void
+    {
+        $this->createContainer();
+
+        $this->assertSame('value', $this->parameter->getCastString('app.internal_array.key'));
+        $this->assertSame('1', $this->parameter->getCastString('app.internal_int'));
+        $this->assertSame('true', $this->parameter->getCastString('app.internal_bool'));
+        $this->assertSame('', $this->parameter->getCastString('app.internal_null'));
+    }
+
+    public function testGetCastStringException(): void
+    {
+        $this->createContainer();
+
+        $this->expectExceptionMessage(
+            'Unable to cast array to string. Please use `get()` method instead of `getCastString()',
+        );
+        $this->parameter->getCastString('app.internal_array');
+    }
+
+    public function testGetCastStringWithDefaultValue(): void
+    {
+        $this->createContainer();
+
+        $this->assertSame('default', $this->parameter->getCastString('app.noExist', 'default'));
+    }
+
     public function testParameterExists(): void
     {
         $this->createContainer();
diff --git a/tests/Redirect/RedirectServiceTest.php b/tests/Redirect/Test.php
similarity index 86%
rename from tests/Redirect/RedirectServiceTest.php
rename to tests/Redirect/Test.php
index 2b076ee..fefe725 100644
--- a/tests/Redirect/RedirectServiceTest.php
+++ b/tests/Redirect/Test.php
@@ -7,14 +7,12 @@
 use PHPUnit\Framework\TestCase;
 use Yii\Service\Tests\Support\TestTrait;
 
-final class RedirectServiceTest extends TestCase
+final class Test extends TestCase
 {
     use TestTrait;
 
     public function testRedirect(): void
     {
-        $this->createContainer();
-
         $redirect = $this->redirect->run('home');
 
         $this->assertSame(302, $redirect->getStatusCode());
@@ -23,8 +21,6 @@ public function testRedirect(): void
 
     public function testRedirectWithArguments(): void
     {
-        $this->createContainer();
-
         $redirect = $this->redirect->run('home', 302, ['id' => 1]);
 
         $this->assertSame(302, $redirect->getStatusCode());
@@ -33,8 +29,6 @@ public function testRedirectWithArguments(): void
 
     public function testRedirectWithCode200(): void
     {
-        $this->createContainer();
-
         $redirect = $this->redirect->run('home', 200);
 
         $this->assertSame(200, $redirect->getStatusCode());
@@ -43,8 +37,6 @@ public function testRedirectWithCode200(): void
 
     public function testRedirectWithQueryParams(): void
     {
-        $this->createContainer();
-
         $redirect = $this->redirect->run('home', 302, [], ['id' => 1]);
 
         $this->assertSame(302, $redirect->getStatusCode());
diff --git a/tests/Support/TestTrait.php b/tests/Support/TestTrait.php
index 1367ab5..3ae369c 100644
--- a/tests/Support/TestTrait.php
+++ b/tests/Support/TestTrait.php
@@ -26,6 +26,11 @@ trait TestTrait
     private Redirect $redirect;
     protected bool $writeToFiles = true;
 
+    public function setup(): void
+    {
+        $this->createContainer();
+    }
+
     public function tearDown(): void
     {
         unset($this->aliases, $this->logger, $this->mailer, $this->parameter, $this->redirect);
diff --git a/tests/data/config/application-params.php b/tests/data/config/application-params.php
index f4bf44e..8edc13b 100644
--- a/tests/data/config/application-params.php
+++ b/tests/data/config/application-params.php
@@ -8,5 +8,9 @@
         'aliases' => [
             'tests' => '@root/tests',
         ],
+        'internal_array' => ['key' => 'value'],
+        'internal_bool' => true,
+        'internal_int' => 1,
+        'internal_null' => null,
     ],
 ];