diff --git a/app/models/openai_models.py b/app/models/openai_models.py
index 9af4308..4f78578 100644
--- a/app/models/openai_models.py
+++ b/app/models/openai_models.py
@@ -16,6 +16,7 @@ class ChatMessage(BaseModel):
     name: Optional[str] = None
     function_call: Optional[Dict[str, Any]] = None
     tool_calls: Optional[List[Dict[str, Any]]] = None
+    tool_call_id: Optional[str] = None
 
 
 class FunctionCall(BaseModel):
@@ -85,6 +86,7 @@ class ChatCompletionChunkDelta(BaseModel):
     content: Optional[Union[str, List[Dict[str, Any]]]] = None
     function_call: Optional[Dict[str, Any]] = None
     tool_calls: Optional[List[Dict[str, Any]]] = None
+    tool_call_id: Optional[str] = None
 
 
 class ChatCompletionChunkChoice(BaseModel):
diff --git a/app/utils/transformers.py b/app/utils/transformers.py
index b0dd182..f35ac34 100644
--- a/app/utils/transformers.py
+++ b/app/utils/transformers.py
@@ -47,6 +47,9 @@ def transform_messages_to_watsonx(messages: List[ChatMessage]) -> List[Dict[str,
         if msg.function_call:
             watsonx_msg["function_call"] = msg.function_call
         
+        if msg.tool_call_id:
+            watsonx_msg["tool_call_id"] = msg.tool_call_id
+        
         watsonx_messages.append(watsonx_msg)
     
     return watsonx_messages