diff --git a/libs/core/langchain_core/language_models/v1/chat_models.py b/libs/core/langchain_core/language_models/v1/chat_models.py
index 93a6449ceaa..bc39787c682 100644
--- a/libs/core/langchain_core/language_models/v1/chat_models.py
+++ b/libs/core/langchain_core/language_models/v1/chat_models.py
@@ -39,7 +39,6 @@ from langchain_core.language_models.base import (
 )
 from langchain_core.messages import (
     AIMessage,
-    BaseMessage,
     convert_to_openai_image_block,
     get_buffer_string,
     is_data_content_block,
@@ -924,13 +923,13 @@ class BaseChatModelV1(BaseLanguageModel[AIMessageV1], ABC):
         Returns:
             The sum of the number of tokens across the messages.
         """
-        messages = [_convert_from_v1_message(message) for message in messages]
+        messages_v0 = [_convert_from_v1_message(message) for message in messages]
         if tools is not None:
             warnings.warn(
                 "Counting tokens in tool schemas is not yet supported. Ignoring tools.",
                 stacklevel=2,
             )
-        return sum(self.get_num_tokens(get_buffer_string([m])) for m in messages)
+        return sum(self.get_num_tokens(get_buffer_string([m])) for m in messages_v0)
 
 
 def _gen_info_and_msg_metadata(
diff --git a/libs/core/langchain_core/messages/v1.py b/libs/core/langchain_core/messages/v1.py
index de0cf4932e9..4726becc1e6 100644
--- a/libs/core/langchain_core/messages/v1.py
+++ b/libs/core/langchain_core/messages/v1.py
@@ -329,9 +329,9 @@ class AIMessageChunk:
         def add_chunk_to_invalid_tool_calls(chunk: ToolCallChunk) -> None:
             invalid_tool_calls.append(
                 create_invalid_tool_call(
-                    name=chunk["name"],
-                    args=chunk["args"],
-                    id=chunk["id"],
+                    name=chunk.get("name", ""),
+                    args=chunk.get("args", ""),
+                    id=chunk.get("id", ""),
                     error=None,
                 )
             )
@@ -342,9 +342,9 @@ class AIMessageChunk:
                 if isinstance(args_, dict):
                     tool_calls.append(
                         create_tool_call(
-                            name=chunk["name"] or "",
+                            name=chunk.get("name", ""),
                             args=args_,
-                            id=chunk["id"],
+                            id=chunk.get("id", ""),
                         )
                     )
                 else: