diff --git a/astrbot/core/agent/message.py b/astrbot/core/agent/message.py
index d69bc6a81..c51ce5008 100644
--- a/astrbot/core/agent/message.py
+++ b/astrbot/core/agent/message.py
@@ -169,6 +169,15 @@ def check_content_required(self):
             )
         return self
 
+    @model_serializer(mode="wrap")
+    def serialize(self, handler):
+        data = handler(self)
+        if self.tool_calls is None:
+            data.pop("tool_calls", None)
+        if self.tool_call_id is None:
+            data.pop("tool_call_id", None)
+        return data
+
 
 class AssistantMessageSegment(Message):
     """A message segment from the assistant."""