diff --git a/src/Controller/Component/CRUDComponent.php b/src/Controller/Component/CRUDComponent.php
index 2c4704d..14f4c4f 100644
--- a/src/Controller/Component/CRUDComponent.php
+++ b/src/Controller/Component/CRUDComponent.php
@@ -184,7 +184,7 @@ class CRUDComponent extends Component
         $this->Controller->set('entity', $data);
     }
 
-    private function prepareValidationMessage($errors)
+    public function prepareValidationMessage($errors)
     {
         $validationMessage = '';
         if (!empty($errors)) {
@@ -280,8 +280,9 @@ class CRUDComponent extends Component
                 $validationErrors = $data->getErrors();
                 $validationMessage = $this->prepareValidationMessage($validationErrors);
                 $message = __(
-                    __('{0} could not be modified.'),
-                    $this->ObjectAlias
+                    '{0} could not be modified.{1}',
+                    $this->ObjectAlias,
+                    empty($validationMessage) ? '' : PHP_EOL . __('Reason:{0}', $validationMessage)
                 );
                 if ($this->Controller->ParamHandler->isRest()) {
                 } else if ($this->Controller->ParamHandler->isAjax()) {
diff --git a/src/Controller/LocalToolsController.php b/src/Controller/LocalToolsController.php
index fe5a384..73e3f83 100644
--- a/src/Controller/LocalToolsController.php
+++ b/src/Controller/LocalToolsController.php
@@ -152,9 +152,6 @@ class LocalToolsController extends AppController
         if (!empty($responsePayload)) {
             return $responsePayload;
         }
-        if ($this->ParamHandler->isAjax() && !empty($this->ajaxResponsePayload)) {
-            return $this->ajaxResponsePayload;
-        }
         $localConnectors = $this->LocalTools->extractMeta($this->LocalTools->getConnectors());
         $dropdownData = ['connectors' => []];
         $connector = false;
diff --git a/src/Lib/default/local_tool_connectors/MispConnector.php b/src/Lib/default/local_tool_connectors/MispConnector.php
index 5d95b45..940db8b 100644
--- a/src/Lib/default/local_tool_connectors/MispConnector.php
+++ b/src/Lib/default/local_tool_connectors/MispConnector.php
@@ -97,26 +97,29 @@ class MispConnector extends CommonConnectorTools
         ]
     ];
     public $version = '0.1';
-    public $parameters = [
+    public $settings = [
         'url' => [
-            'required' => true,
-            // 'validation' => 'url',
+            'type' => 'text'
         ],
         'authkey' => [
-            'required' => true,
-            // 'validation' => 'authkeyLength',
+            'type' => 'text'
         ],
         'skip_ssl' => [
-            // 'validation' => 'boolean',
+            'type' => 'boolean'
         ],
-        'test_param' => [
-            'options' => [
-                'John',
-                'Doe'
-            ]
-        ]
     ];
 
+    public function addSettingValidatorRules($validator)
+    {
+        return $validator
+            ->requirePresence('url')
+            ->notEmpty('url', __('An URL must be provided'))
+            ->requirePresence('authkey')
+            ->notEmpty('authkey', __('An Authkey must be provided'))
+            ->lengthBetween('authkey', [40, 40], __('The authkey must be 40 character long'))
+            ->boolean('skip_ssl');
+    }
+
     public function addExposedFunction(string $functionName): void
     {
         $this->exposedFunctions[] = $functionName;
diff --git a/src/Model/Table/LocalToolsTable.php b/src/Model/Table/LocalToolsTable.php
index 8bbe098..d061ba3 100644
--- a/src/Model/Table/LocalToolsTable.php
+++ b/src/Model/Table/LocalToolsTable.php
@@ -4,6 +4,7 @@ namespace App\Model\Table;
 
 use App\Model\Table\AppTable;
 use Cake\ORM\Table;
+use Cake\ORM\RulesChecker;
 use Cake\Validation\Validator;
 use Migrations\Migrations;
 use Cake\Filesystem\Folder;
@@ -33,7 +34,14 @@ class LocalToolsTable extends AppTable
 
     public function validationDefault(Validator $validator): Validator
     {
-        return $validator;
+        return $validator->add('settings', 'validSettings', [
+                'rule' => 'isValidSettings',
+                'provider' => 'table',
+                'message' => __('Invalid settings'),
+                'on' => function ($context) {
+                    return !empty($context['data']['settings']);
+                }
+            ]);
     }
 
     public function loadConnector(string $connectorName): void
@@ -133,7 +141,7 @@ class LocalToolsTable extends AppTable
                 'connector' => $connector_type,
                 'connector_version' => $connector_class->version,
                 'connector_description' => $connector_class->description,
-                'connector_parameters' => $connector_class->parameters ?? []
+                'connector_settings' => $connector_class->settings ?? []
             ];
             if ($includeConnections) {
                 $connector['connections'] = $this->healthCheck($connector_type, $connector_class);
@@ -298,4 +306,32 @@ class LocalToolsTable extends AppTable
         }
         return $connection;
     }
+
+    public function isValidSettings($settings, array $context)
+    {
+        $settings = json_decode($settings, true);
+        $validationErrors = $this->getLocalToolsSettingValidationErrors($context['data']['id'], $settings);
+        return $this->getValidationMessage($validationErrors);
+    }
+
+    public function getValidationMessage($validationErrors)
+    {
+        $messages = [];
+        foreach ($validationErrors as $key => $errors) {
+            $messages[] = sprintf('%s: %s', $key, implode(', ', $errors));
+        }
+        return empty($messages) ? true : implode('; ', $messages);
+    }
+
+    public function getLocalToolsSettingValidationErrors($connectionId, array $settings): array
+    {
+        $connector = array_values($this->getConnectorByConnectionId($connectionId))[0];
+        $errors = [];
+        if (method_exists($connector, 'addSettingValidatorRules')) {
+            $validator = new Validator();
+            $validator = $connector->addSettingValidatorRules($validator);
+            $errors = $validator->validate($settings);
+        }
+        return $errors;
+    }
 }
diff --git a/templates/LocalTools/add.php b/templates/LocalTools/add.php
index 02aa7d9..184f0e6 100644
--- a/templates/LocalTools/add.php
+++ b/templates/LocalTools/add.php
@@ -21,7 +21,7 @@
                     'type' => 'codemirror',
                     'codemirror' => [
                         'height' => '10rem',
-                        'hints' => $connectors[0]['connector_parameters']
+                        'hints' => $connectors[0]['connector_settings']
                     ]
                 ],
                 [
diff --git a/templates/element/genericElements/Form/Fields/codemirrorField.php b/templates/element/genericElements/Form/Fields/codemirrorField.php
index b5f9c00..1ca79ab 100644
--- a/templates/element/genericElements/Form/Fields/codemirrorField.php
+++ b/templates/element/genericElements/Form/Fields/codemirrorField.php
@@ -1,9 +1,4 @@
 <?php
-    // $randomVal = Cake\Utility\Security::randomString(8);
-    // $params['type'] = 'textarea';
-    // $textareaClass = "area-for-codemirror-{$randomVal}";
-    // $params['class'] = [$textareaClass];
-    // echo $this->FormFieldMassage->prepareFormElement($this->Form, $params, $fieldData);
     echo $this->element('genericElements/codemirror', [
         'data' => $fieldData,
         'params' => $params,
diff --git a/templates/element/genericElements/codemirror.php b/templates/element/genericElements/codemirror.php
index f52ff25..dd2ad65 100644
--- a/templates/element/genericElements/codemirror.php
+++ b/templates/element/genericElements/codemirror.php
@@ -68,9 +68,23 @@
             }
             cm.save()
         })
+        registerObserver(cm, $textArea[0])
+        synchronizeClasses(cm, $textArea[0])
         postInit()
     }
 
+    // Used to synchronize textarea classes (such as `is-invalid` for content validation)
+    function registerObserver(cm, textarea) {
+        const observer = new MutationObserver(function(mutations) {
+            mutations.forEach(function(mutation) {
+                if (mutation.attributeName == 'class') {
+                    synchronizeClasses(cm, textarea)
+                }
+            });    
+        });
+        observer.observe(textarea, {attributes: true})
+    }
+
     function postInit() {
         if ($(cm.getInputField()).closest('.modal').length) { // editor is in modal
             setTimeout(() => {
@@ -79,6 +93,14 @@
         }
     }
 
+    function synchronizeClasses(cm, textarea) {
+        const classes = Array.from(textarea.classList).filter(c => !c.startsWith('area-for-codemirror'))
+        const $wrapper = $(cm.getWrapperElement())
+        classes.forEach(c => {
+            $wrapper.toggleClass(c)
+        });
+    }
+
     function jsonHints() {
         const cur = cm.getCursor()
         const token = cm.getTokenAt(cur)
@@ -130,7 +152,7 @@
         if (str.length > 0) {
             let validHints = []
             let hint
-            for (let i = 0; hints.length < cmOptions.hintOptions.maxHints && i < validHints.length; i++) {
+            for (let i = 0; validHints.length < cmOptions.hintOptions.maxHints && i < hints.length; i++) {
                 if (hints[i].text.startsWith(str)) {
                     validHints.push(hints[i])
                 }
diff --git a/webroot/css/CodeMirror/codemirror-additional.css b/webroot/css/CodeMirror/codemirror-additional.css
index 4c0ae6e..0c62e18 100644
--- a/webroot/css/CodeMirror/codemirror-additional.css
+++ b/webroot/css/CodeMirror/codemirror-additional.css
@@ -6,3 +6,24 @@
 .CodeMirror-gutters {
     border-radius: 0.25rem 0 0 0.25rem;
 }
+
+.CodeMirror.is-invalid {
+    border-color: #dc3545;
+    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='none' stroke='%23dc3545' viewBox='0 0 12 12'%3e%3ccircle cx='6' cy='6' r='4.5'/%3e%3cpath stroke-linejoin='round' d='M5.8 3.6h.4L6 6.5z'/%3e%3ccircle cx='6' cy='8.2' r='.6' fill='%23dc3545' stroke='none'/%3e%3c/svg%3e");
+    background-repeat: no-repeat;
+    background-position: right calc(0.375em + 0.1875rem) center;
+    background-size: calc(0.75em + 0.375rem) calc(0.75em + 0.375rem);
+    background-position: top calc(0.375em + 0.1875rem) right calc(0.375em + 0.1875rem);
+}
+
+.CodeMirror.is-invalid .CodeMirror-gutters {
+    /* background-color: #dc3545 !important; */
+}
+
+.CodeMirror.is-invalid .CodeMirror-linenumber {
+    /* color: white !important; */
+}
+
+.CodeMirror-hints {
+    z-index: 1060 !important; /* Make sure hint is above modal */
+}
\ No newline at end of file