diff --git a/tools/webex-public-workspace/webex-messaging/list-direct-messages.js b/tools/webex-public-workspace/webex-messaging/list-direct-messages.js
index 277284c..f5206cf 100644
--- a/tools/webex-public-workspace/webex-messaging/list-direct-messages.js
+++ b/tools/webex-public-workspace/webex-messaging/list-direct-messages.js
@@ -13,7 +13,7 @@ const executeFunction = async ({ parentId, personId, personEmail }) => {
   try {
     // Construct the URL with query parameters
     const url = new URL(getWebexUrl('/messages/direct'));
-    url.searchParams.append('parentId', parentId);
+    if (parentId) url.searchParams.append('parentId', parentId);
 
     // Add either personId OR personEmail, not both
     if (personId) {
@@ -82,4 +82,4 @@ const apiTool = {
   }
 };
 
-export { apiTool };
\ No newline at end of file
+export { apiTool };