diff --git a/vision_agent/tools/tool_utils.py b/vision_agent/tools/tool_utils.py
index f0304653..b87689c4 100644
--- a/vision_agent/tools/tool_utils.py
+++ b/vision_agent/tools/tool_utils.py
@@ -14,14 +14,13 @@
 def _send_inference_request(
     payload: Dict[str, Any], endpoint_name: str
 ) -> Dict[str, Any]:
-    # runtime_tag is used to differentiate different internal callers
-    runtime_tag = os.environ.get("RUNTIME_TAG", "")
+    if runtime_tag := os.environ.get("RUNTIME_TAG", ""):
+        payload["runtime_tag"] = runtime_tag
     res = requests.post(
         f"{_LND_API_URL}/model/{endpoint_name}",
         headers={
             "Content-Type": "application/json",
             "apikey": _LND_API_KEY,
-            "runtime-tag": runtime_tag,
         },
         json=payload,
     )