diff --git a/lib/client.js b/lib/client.js
index be37288..44f288c 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -355,8 +355,9 @@ export class RealtimeClient extends RealtimeEventHandler {
       if (item.status === 'completed') {
         this.dispatch('conversation.item.completed', { item });
       }
-      if (item.formatted.tool) {
-        callTool(item.formatted.tool);
+      const tool = item.formatted.tool;
+      if (tool && this.tools[tool.name]?.handler) {
+        callTool(tool);
       }
     });