diff --git a/OutOfSchool/OutOfSchool.WebApi/Common/Resources/Codes/ImagesOperationErrorCode.cs b/OutOfSchool/OutOfSchool.WebApi/Common/Resources/Codes/ImagesOperationErrorCode.cs
index 92765f5cdd..843e7d55d3 100644
--- a/OutOfSchool/OutOfSchool.WebApi/Common/Resources/Codes/ImagesOperationErrorCode.cs
+++ b/OutOfSchool/OutOfSchool.WebApi/Common/Resources/Codes/ImagesOperationErrorCode.cs
@@ -1,43 +1,85 @@
 namespace OutOfSchool.WebApi.Common.Resources.Codes
 {
+    /// <summary>
+    /// Contains error codes of all operations with images.
+    /// </summary>
     public enum ImagesOperationErrorCode
     {
+        /// <summary>
+        /// The default error.
+        /// </summary>
         [ResourcesKey(nameof(DefaultError))]
         DefaultError = 0,
 
+        /// <summary>
+        /// The error that can be used when something wrong has happened while uploading images.
+        /// </summary>
         [ResourcesKey(nameof(UploadingError))]
         UploadingError = 1,
 
+        /// <summary>
+        /// The error that can be used when something wrong has happened while removing images.
+        /// </summary>
         [ResourcesKey(nameof(RemovingError))]
         RemovingError = 2,
 
+        /// <summary>
+        /// The error that can be used when unable to make some operation because of an image storage.
+        /// </summary>
         [ResourcesKey(nameof(ImageStorageError))]
         ImageStorageError = 3,
 
+        /// <summary>
+        /// The error that can be used when some image has not found.
+        /// </summary>
         [ResourcesKey(nameof(ImageNotFoundError))]
         ImageNotFoundError = 4,
 
+        /// <summary>
+        /// The error that can be used when some image hasn't passed the validation process because of unexpected factors.
+        /// </summary>
         [ResourcesKey(nameof(UnexpectedValidationError))]
         UnexpectedValidationError = 5,
 
+        /// <summary>
+        /// The error that can be used when some image hasn't passed the validation process because of the invalid image size.
+        /// </summary>
         [ResourcesKey(nameof(InvalidSizeError))]
         InvalidSizeError = 6,
 
+        /// <summary>
+        /// The error that can be used when some image hasn't passed the validation process because of the invalid image format.
+        /// </summary>
         [ResourcesKey(nameof(InvalidFormatError))]
         InvalidFormatError = 7,
 
+        /// <summary>
+        /// The error that can be used when some image hasn't passed the validation process because of the invalid image resolution.
+        /// </summary>
         [ResourcesKey(nameof(InvalidResolutionError))]
         InvalidResolutionError = 8,
 
+        /// <summary>
+        /// The error that can be used when cannot find the entity for operations with images.
+        /// </summary>
         [ResourcesKey(nameof(EntityNotFoundError))]
         EntityNotFoundError = 9,
 
+        /// <summary>
+        /// The error that can be used when no images were given for making operations.
+        /// </summary>
         [ResourcesKey(nameof(NoGivenImagesError))]
         NoGivenImagesError = 10,
 
+        /// <summary>
+        /// The error that can be used when something wrong has happened while updating the entity with changed images.
+        /// </summary>
         [ResourcesKey(nameof(UpdateEntityError))]
         UpdateEntityError = 11,
 
+        /// <summary>
+        /// The error that can be used when count of images is more than allowed for this type of entity.
+        /// </summary>
         [ResourcesKey(nameof(ExceedingCountOfImagesError))]
         ExceedingCountOfImagesError = 12,
     }
diff --git a/OutOfSchool/OutOfSchool.WebApi/Extensions/OperationExtensions.cs b/OutOfSchool/OutOfSchool.WebApi/Extensions/OperationExtensions.cs
index 50653b6052..d98f0ad06a 100644
--- a/OutOfSchool/OutOfSchool.WebApi/Extensions/OperationExtensions.cs
+++ b/OutOfSchool/OutOfSchool.WebApi/Extensions/OperationExtensions.cs
@@ -6,13 +6,28 @@
 
 namespace OutOfSchool.WebApi.Extensions
 {
+    /// <summary>
+    /// Extensions for app service operations.
+    /// </summary>
     public static class OperationExtensions
     {
+        /// <summary>
+        /// Returns the <see cref="OperationError"/> localized for the specified culture by the <see cref="ImagesOperationErrorCode"/> code.
+        /// </summary>
+        /// <param name="code">The <see cref="ImagesOperationErrorCode"/> code.</param>
+        /// <returns>The <see cref="OperationError"/> localized for the specified culture.</returns>
         public static OperationError GetOperationError(this ImagesOperationErrorCode code)
         {
             return CreateOperationError(code.ToString(), code.GetResourceValue());
         }
 
+        /// <summary>
+        /// Creates a new instance of <see cref="OperationError"/>.
+        /// </summary>
+        /// <param name="code">Code of the error.</param>
+        /// <param name="description">Error's description.</param>
+        /// <returns>The instance of <see cref="OperationError"/>.</returns>
+        /// <exception cref="ArgumentException">When <c>code</c> is null.</exception>
         public static OperationError CreateOperationError(string code, string description)
         {
             if (string.IsNullOrEmpty(code))
diff --git a/OutOfSchool/OutOfSchool.WebApi/Extensions/RetrievingResourcesExtensions.cs b/OutOfSchool/OutOfSchool.WebApi/Extensions/RetrievingResourcesExtensions.cs
index fbaf286f4f..bee914cf32 100644
--- a/OutOfSchool/OutOfSchool.WebApi/Extensions/RetrievingResourcesExtensions.cs
+++ b/OutOfSchool/OutOfSchool.WebApi/Extensions/RetrievingResourcesExtensions.cs
@@ -9,8 +9,17 @@
 
 namespace OutOfSchool.WebApi.Extensions
 {
+    /// <summary>
+    /// Extensions for receiving essential data from app resources.
+    /// </summary>
     public static class RetrievingResourcesExtensions
     {
+        /// <summary>
+        /// Returns the value of the string resource localized for the specified culture by the <see cref="ImagesOperationErrorCode"/> code.
+        /// </summary>
+        /// <param name="code">The <see cref="ImagesOperationErrorCode"/> code.</param>
+        /// <param name="culture">The culture you wanna try to get resource value.</param>
+        /// <returns>The value of the resource localized for the specified culture, or <c>null</c> if a resource key cannot be found in a resource set.</returns>
         public static string GetResourceValue(this ImagesOperationErrorCode code, CultureInfo culture = null)
         {
             var resourceKey = TryGetResourceKey(code);
@@ -18,8 +27,21 @@ public static string GetResourceValue(this ImagesOperationErrorCode code, Cultur
             return GetStringFromResources(ResourceManagers.ImageResourceManager, resourceKey, culture);
         }
 
+        /// <summary>
+        /// Returns the value of the resource key by the <see cref="ImagesOperationErrorCode"/> code.
+        /// </summary>
+        /// <param name="code">The <see cref="ImagesOperationErrorCode"/> code.</param>
+        /// <returns>The value of the resource key, or <c>null</c> if a resource key cannot be found in an <see cref="ImagesOperationErrorCode"/> set.</returns>
         public static string GetResourceKey(this ImagesOperationErrorCode code) => TryGetResourceKey(code);
 
+        /// <summary>
+        /// Returns the value of the string resource localized for the specified culture.
+        /// </summary>
+        /// <param name="resourceManager">The resource manager.</param>
+        /// <param name="resourceKey">The key to find resource value.</param>
+        /// <param name="culture">The culture you wanna try to get resource value.</param>
+        /// <returns>The value of the resource localized for the specified culture, or <c>null</c> if a resource key cannot be found in a resource set.</returns>
+        /// <exception cref="ArgumentNullException">When resourceManager is null.</exception>
         internal static string GetStringFromResources(ResourceManager resourceManager, string resourceKey, CultureInfo culture = null)
         {
             _ = resourceManager ?? throw new ArgumentNullException(nameof(resourceManager));