diff --git a/libs/partners/anthropic/langchain_anthropic/chat_models.py b/libs/partners/anthropic/langchain_anthropic/chat_models.py
index 68bfca2eefa..dcabd30b647 100644
--- a/libs/partners/anthropic/langchain_anthropic/chat_models.py
+++ b/libs/partners/anthropic/langchain_anthropic/chat_models.py
@@ -1210,12 +1210,14 @@ def _make_message_chunk_from_anthropic_event(
             content_block = event.delta.model_dump()
             content_block["index"] = event.index
             content_block["type"] = "tool_use"
-            tool_call_chunk = create_tool_call_chunk(**{
-                "index": event.index,
-                "id": None,
-                "name": None,
-                "args": event.delta.partial_json,
-            })
+            tool_call_chunk = create_tool_call_chunk(
+                **{
+                    "index": event.index,
+                    "id": None,
+                    "name": None,
+                    "args": event.delta.partial_json,
+                }
+            )
             message_chunk = AIMessageChunk(
                 content=[content_block],
                 tool_call_chunks=[tool_call_chunk],  # type: ignore