diff --git a/lib/tasks/llm/index.js b/lib/tasks/llm/index.js
index 68b8ca68..a0c93772 100644
--- a/lib/tasks/llm/index.js
+++ b/lib/tasks/llm/index.js
@@ -114,8 +114,14 @@ class TaskLlm extends Task {
     const tool_response = await this.cs?.requestor.request('llm:tool-call', this.toolHook, {tool_call_id, ...data});
     // if the toolHook was a websocket it will return undefined, otherwise it should return an object
     if (typeof tool_response != 'undefined') {
-      tool_response.type = 'client_tool_result';
-      tool_response.invocation_id = tool_call_id;
+      // If the webhook didn't declare a `type`, assume the legacy Ultravox-style
+      // envelope and fill it in. Otherwise pass the response through unchanged so
+      // vendors like OpenAI ('conversation.item.create') receive the exact shape
+      // their realtime API expects.
+      if (!tool_response.type) {
+        tool_response.type = 'client_tool_result';
+        tool_response.invocation_id = tool_call_id;
+      }
       this.processToolOutput(tool_call_id, tool_response);
     }
   }