diff --git a/src/ApiGenerator.php b/src/ApiGenerator.php
index e9b9e39..e12995a 100644
--- a/src/ApiGenerator.php
+++ b/src/ApiGenerator.php
@@ -28,6 +28,7 @@ public function handle()
         try {
             $this->actionIndex($ramlFile);
         } catch (\Exception $e) {
+            $this->info($e->getMessage());
             $this->error($e->getTraceAsString());
         }
     }
diff --git a/src/controllers/BaseCommand.php b/src/controllers/BaseCommand.php
index 13d2c9c..8849d82 100644
--- a/src/controllers/BaseCommand.php
+++ b/src/controllers/BaseCommand.php
@@ -88,8 +88,22 @@ public function actionIndex(string $file)
      */
     private function validate()
     {
+        // required yaml fields will be thrown as exceptions
         if (empty($this->data[ApiInterface::OPEN_API_KEY])) {
-            throw new SchemaException('There must be ' . ApiInterface::OPEN_API_KEY . ' document root field');
+            throw new SchemaException('There must be ' . ApiInterface::OPEN_API_KEY . ', ' . ApiInterface::API_SERVERS . ' document root fields');
+        }
+
+        $schemas = $this->data[ApiInterface::API_COMPONENTS][ApiInterface::API_SCHEMAS];
+        if (empty($schemas[CustomsInterface::CUSTOM_TYPES_ID])
+            || empty($schemas[CustomsInterface::CUSTOM_TYPES_TYPE])
+            || empty($schemas[CustomsInterface::CUSTOM_RELATIONSHIPS_DATA_ITEM])) {
+            throw new SchemaException('At least these types must be declared: ' . CustomsInterface::CUSTOM_TYPES_ID
+                . ', ' . CustomsInterface::CUSTOM_TYPES_TYPE . ', ' . CustomsInterface::CUSTOM_RELATIONSHIPS_DATA_ITEM
+                . ' as components -> schemas descendants');
+        }
+
+        if (empty($this->data[ApiInterface::API_INFO])) {
+            $this->warn(ApiInterface::API_INFO . ': field would be convenient to show users what this API is about');
         }
     }
 
@@ -104,7 +118,7 @@ private function generateOpenApi()
         $this->migrationsDir  = DirsInterface::MIGRATIONS_DIR;
 
         foreach ($this->data[ApiInterface::API_SERVERS] as $server) {
-            $vars = $server[ApiInterface::API_VARS];
+            $vars          = $server[ApiInterface::API_VARS];
             $this->version = $vars[ApiInterface::API_BASE_PATH][ApiInterface::API_DEFAULT];
 
             if (env('APP_ENV') === 'dev') { // for test env based on .env
diff --git a/src/types/ApiInterface.php b/src/types/ApiInterface.php
index 1bd0682..cd5dba3 100644
--- a/src/types/ApiInterface.php
+++ b/src/types/ApiInterface.php
@@ -6,6 +6,7 @@ interface ApiInterface
 {
     public const OPEN_API_KEY = 'openapi';
     public const API_SERVERS  = 'servers';
+    public const API_INFO     = 'info';
 
     public const API_VARS       = 'variables';
     public const API_BASE_PATH  = 'basePath';
diff --git a/src/types/CustomsInterface.php b/src/types/CustomsInterface.php
index b945c0e..c2770d7 100644
--- a/src/types/CustomsInterface.php
+++ b/src/types/CustomsInterface.php
@@ -1,15 +1,18 @@
 <?php
+
 namespace rjapi\types;
 
 interface CustomsInterface
 {
-    public const CUSTOM_TYPES_ID                          = 'ID';
-    public const CUSTOM_TYPES_TYPE                        = 'Type';
-    public const CUSTOM_TYPES_RELATIONSHIPS               = 'Relationships';
-    public const CUSTOM_TYPES_QUERY_PARAMS                = 'QueryParams';
-    public const CUSTOM_TYPES_FILTER                      = 'Filter';
-    public const CUSTOM_TYPES_ATTRIBUTES                  = 'Attributes';
-    public const CUSTOM_TYPES_TREES                       = 'Trees';
-    public const CUSTOM_PROP_JWT                          = 'jwt';
-    public const CUSTOM_TYPE_REDIS                        = 'Redis';
+    public const CUSTOM_TYPES_ID                = 'ID';
+    public const CUSTOM_TYPES_TYPE              = 'Type';
+    public const CUSTOM_RELATIONSHIPS_DATA_ITEM = 'RelationshipsDataItem';
+
+    public const CUSTOM_TYPES_RELATIONSHIPS = 'Relationships';
+    public const CUSTOM_TYPES_QUERY_PARAMS  = 'QueryParams';
+    public const CUSTOM_TYPES_FILTER        = 'Filter';
+    public const CUSTOM_TYPES_ATTRIBUTES    = 'Attributes';
+    public const CUSTOM_TYPES_TREES         = 'Trees';
+    public const CUSTOM_PROP_JWT            = 'jwt';
+    public const CUSTOM_TYPE_REDIS          = 'Redis';
 }
\ No newline at end of file