diff --git a/app/agent/__init__.py b/app/agent/__init__.py
index 4b75961..23f26f4 100644
--- a/app/agent/__init__.py
+++ b/app/agent/__init__.py
@@ -1,7 +1,7 @@
 from app.agent.base import BaseAgent
 from app.agent.browser import BrowserAgent
-from app.agent.mcp import MCPAgent
 from app.agent.cot import CoTAgent
+from app.agent.mcp import MCPAgent
 from app.agent.planning import PlanningAgent
 from app.agent.react import ReActAgent
 from app.agent.swe import SWEAgent
diff --git a/app/agent/cot.py b/app/agent/cot.py
index 66106e5..a7bd57e 100644
--- a/app/agent/cot.py
+++ b/app/agent/cot.py
@@ -1,10 +1,10 @@
-from typing import List, Optional
+from typing import Optional
 
 from pydantic import Field
 
 from app.agent.base import BaseAgent
-from app.logger import logger
 from app.llm import LLM
+from app.logger import logger
 from app.prompt.cot import NEXT_STEP_PROMPT, SYSTEM_PROMPT
 from app.schema import AgentState, Message
 
@@ -33,7 +33,9 @@ class CoTAgent(BaseAgent):
         # Use system prompt and user messages
         response = await self.llm.ask(
             messages=self.messages,
-            system_msgs=[Message.system_message(self.system_prompt)] if self.system_prompt else None
+            system_msgs=[Message.system_message(self.system_prompt)]
+            if self.system_prompt
+            else None,
         )
 
         # Record assistant's response