Ensure action has a description when being exposed via MCP

Author: C0nquistadore

src/Dibix.Sdk.CodeGeneration/Validation/EndpointModelValidator.cs

@@ -128,7 +128,7 @@ private bool ValidateAmbiguousActionNames(IEnumerable<ActionRegistration> action
 
         private bool ValidateAction(ActionDefinition action)
         {
-            bool isValid = ValidateReservedPathSegments(action) && ValidateParameters(action) && ValidateBodyAllowedForMethod(action);
+            bool isValid = ValidateReservedPathSegments(action) && ValidateParameters(action) && ValidateBodyAllowedForMethod(action) && ValidateMcpDescription(action);
             return isValid;
         }
 
@@ -194,6 +194,19 @@ private bool ValidateBodyAllowedForMethod(ActionDefinition action)
             return isValid;
         }
 
+        // [warning] Tool GetTemplateDefinition does not have a description. Tools must be accurately described to be called
+        private bool ValidateMcpDescription(ActionDefinition actionDefinition)
+        {
+            if (actionDefinition.ModelContextProtocolType == ModelContextProtocolType.None)
+                return true;
+
+            if (actionDefinition.Description != null)
+                return true;
+
+            _logger.LogError($"A description for action '{actionDefinition.OperationId}' must be provided, when being exposed via MCP", actionDefinition.Location);
+            return false;
+        }
+
         // When using the BODY.$RAW property source, the raw body will be passed to as a stream to an SqlParameter.
         // The stream will be only accessed asynchronously if one of the async ADO.NET methods is used.
         // Otherwise, it will cause this exception in the ASP.NET core host: