diff --git a/nanobot/agent/tools/cron.py b/nanobot/agent/tools/cron.py
index 9989af55f..00f726c08 100644
--- a/nanobot/agent/tools/cron.py
+++ b/nanobot/agent/tools/cron.py
@@ -74,7 +74,7 @@ class CronTool(Tool):
                     "enum": ["add", "list", "remove"],
                     "description": "Action to perform",
                 },
-                "message": {"type": "string", "description": "Reminder message (for add)"},
+                "message": {"type": "string", "description": "Instruction for the agent to execute when the job triggers (e.g., 'Send a reminder to WeChat: xxx' or 'Check system status and report')"},
                 "every_seconds": {
                     "type": "integer",
                     "description": "Interval in seconds (for recurring tasks)",