diff --git a/agent/deep_assistant.py b/agent/deep_assistant.py
index 7933792..f8183aa 100644
--- a/agent/deep_assistant.py
+++ b/agent/deep_assistant.py
@@ -220,7 +220,7 @@ async def init_agent(config: AgentConfig):
     middleware.append(ToolUseCleanupMiddleware())
     # 添加工具输出长度控制中间件
     tool_output_middleware = ToolOutputLengthMiddleware(
-        max_length=getattr(config.generate_cfg, 'tool_output_max_length', None) if config.generate_cfg else None or TOOL_OUTPUT_MAX_LENGTH,
+        max_length=(getattr(config.generate_cfg, 'tool_output_max_length', None) if config.generate_cfg else None) or TOOL_OUTPUT_MAX_LENGTH,
         truncation_strategy=getattr(config.generate_cfg, 'tool_output_truncation_strategy', 'smart') if config.generate_cfg else 'smart',
         tool_filters=getattr(config.generate_cfg, 'tool_output_filters', None) if config.generate_cfg else None,
         exclude_tools=getattr(config.generate_cfg, 'tool_output_exclude', []) if config.generate_cfg else [],
diff --git a/agent/tool_output_length_middleware.py b/agent/tool_output_length_middleware.py
index 96b6c1e..18fc3b6 100644
--- a/agent/tool_output_length_middleware.py
+++ b/agent/tool_output_length_middleware.py
@@ -53,7 +53,7 @@ class ToolOutputLengthMiddleware(AgentMiddleware):
             preserve_json: Whether to preserve JSON structure in smart mode
             ellipsis: Text to append when truncating
         """
-        self.max_length = max_length
+        self.max_length = max_length if max_length is not None else 2000  # 确保 max_length 不为 None
         self.truncation_strategy = truncation_strategy
         self.tool_filters = tool_filters
         self.exclude_tools = exclude_tools or []