diff --git a/api/core/agent/fc_agent_runner.py b/api/core/agent/fc_agent_runner.py
index dcc1326b33..f22ee6baa0 100644
--- a/api/core/agent/fc_agent_runner.py
+++ b/api/core/agent/fc_agent_runner.py
@@ -187,7 +187,7 @@ class FunctionCallAgentRunner(BaseAgentRunner):
                     ),
                 )
 
-            assistant_message = AssistantPromptMessage(content="", tool_calls=[])
+            assistant_message = AssistantPromptMessage(content=response, tool_calls=[])
             if tool_calls:
                 assistant_message.tool_calls = [
                     AssistantPromptMessage.ToolCall(
@@ -199,8 +199,6 @@ class FunctionCallAgentRunner(BaseAgentRunner):
                     )
                     for tool_call in tool_calls
                 ]
-            else:
-                assistant_message.content = response
 
             self._current_thoughts.append(assistant_message)
 
diff --git a/api/core/model_runtime/entities/message_entities.py b/api/core/model_runtime/entities/message_entities.py
index 89dae2dbff..fa74f35d28 100644
--- a/api/core/model_runtime/entities/message_entities.py
+++ b/api/core/model_runtime/entities/message_entities.py
@@ -249,10 +249,7 @@ class AssistantPromptMessage(PromptMessage):
 
         :return: True if prompt message is empty, False otherwise
         """
-        if not super().is_empty() and not self.tool_calls:
-            return False
-
-        return True
+        return super().is_empty() and not self.tool_calls
 
 
 class SystemPromptMessage(PromptMessage):