diff --git a/tools/cronjob_tools.py b/tools/cronjob_tools.py
index c62eb4ba1c4..18c68a7ce91 100644
--- a/tools/cronjob_tools.py
+++ b/tools/cronjob_tools.py
@@ -706,7 +706,7 @@ Important safety rule: cron-run sessions should not recursively schedule more cr
         "properties": {
             "action": {
                 "type": "string",
-                "description": "One of: create, list, update, pause, resume, remove, run"
+                "description": "One of: create, list, update, pause, resume, remove, run. When action=create, the 'schedule' and 'prompt' fields are REQUIRED."
             },
             "job_id": {
                 "type": "string",
@@ -718,7 +718,7 @@ Important safety rule: cron-run sessions should not recursively schedule more cr
             },
             "schedule": {
                 "type": "string",
-                "description": "For create/update: '30m', 'every 2h', '0 9 * * *', or ISO timestamp"
+                "description": "REQUIRED for action=create. For create/update: '30m', 'every 2h', '0 9 * * *', or ISO timestamp. Examples: '30m' (every 30 minutes), 'every 2h' (every 2 hours), '0 9 * * *' (daily at 9am), '2026-06-01T09:00:00' (one-shot). You MUST include this field when action=create."
             },
             "name": {
                 "type": "string",