diff --git a/app/flow/planning.py b/app/flow/planning.py
index b60596a88..a7e3a5899 100644
--- a/app/flow/planning.py
+++ b/app/flow/planning.py
@@ -154,7 +154,7 @@ async def _create_initial_plan(self, request: str) -> None:
         if len(agents_description) > 1:
             # Add description of agents to select
             system_message_content += (
-                f"\nNow we have {agents_description} agents. "
+                f"\nNow we have {len(agents_description)} agents. "
                 f"The infomation of them are below: {json.dumps(agents_description)}\n"
                 "When creating steps in the planning tool, please specify the agent names using the format '[agent_name]'."
             )