diff --git a/gateway/platforms/api_server.py b/gateway/platforms/api_server.py
index d9b3287398..82412e5dfc 100644
--- a/gateway/platforms/api_server.py
+++ b/gateway/platforms/api_server.py
@@ -564,8 +564,10 @@ class APIServerAdapter(BasePlatformAdapter):
                 if delta is not None:
                     _stream_q.put(delta)
 
-            def _on_tool_progress(name, preview, args):
+            def _on_tool_progress(event_type, name, preview, args, **kwargs):
                 """Inject tool progress into the SSE stream for Open WebUI."""
+                if event_type != "tool.started":
+                    return  # Only show tool start events in chat stream
                 if name.startswith("_"):
                     return  # Skip internal events (_thinking)
                 from agent.display import get_tool_emoji