diff --git a/internal/tools/cron.go b/internal/tools/cron.go
index b6428754..68711381 100644
--- a/internal/tools/cron.go
+++ b/internal/tools/cron.go
@@ -28,44 +28,91 @@ func (t *CronTool) SetConfigPermStore(s store.ConfigPermissionStore) {
 func (t *CronTool) Name() string { return "cron" }
 
 func (t *CronTool) Description() string {
-	return `Manage Gateway cron jobs (status/list/add/update/remove/run/runs).
+	return `Manage Gateway cron jobs.
+	Always send a JSON object with an "action" field.
 
-ACTIONS:
-- status: Check cron scheduler status
-- list: List jobs (use includeDisabled:true to include disabled)
-- add: Create job (requires job object, see schema below)
-- update: Modify job (requires jobId + patch object)
-- remove: Delete job (requires jobId)
-- run: Trigger job immediately (requires jobId)
-- runs: Get job run history (requires jobId)
+	VALID ACTIONS AND EXACT PAYLOAD SHAPES:
+	1) status
+	{
+	"action": "status"
+	}
 
-JOB SCHEMA (for add action):
-{
-  "name": "string (required, lowercase slug)",
-  "schedule": { ... },      // Required: when to run
-  "message": "string",      // Required: what message to send to the agent
-  "deliver": true|false,    // Optional: deliver result to channel (default false)
-  "channel": "channel-name", // Optional: target channel for delivery (auto-filled from context)
-  "to": "chat-id",          // Optional: target chat/recipient ID
-  "agentId": "agent-uuid",  // Optional: which agent handles the job (default: current)
-  "deleteAfterRun": true    // Optional: auto-delete after execution (default true for "at" schedule)
-}
+	2) list
+	{
+	"action": "list",
+	"includeDisabled": true|false   // optional, default false
+	}
 
-SCHEDULE TYPES (schedule.kind):
-- "at": One-shot at absolute time
-  { "kind": "at", "atMs": <unix-milliseconds> }
-- "every": Recurring interval
-  { "kind": "every", "everyMs": <interval-ms> }
-- "cron": Cron expression
-  { "kind": "cron", "expr": "<5-field cron expression>", "tz": "<optional IANA timezone, e.g. Asia/Ho_Chi_Minh; omit to use gateway default>" }
+	3) add
+	{
+	"action": "add",
+	"job": {
+		"name": "string",             // required, lowercase slug: [a-z0-9-]+
+		"schedule": { ... },          // required
+		"message": "string",          // required
+		"deliver": true|false,        // optional, default false
+		"channel": "string",          // optional
+		"to": "string",               // optional
+		"agentId": "string",          // optional, defaults to current agent
+		"deleteAfterRun": true|false  // optional, default true for schedule.kind="at"
+	}
+	}
 
-CRITICAL CONSTRAINTS:
-- "name" must be a valid slug (lowercase letters, numbers, hyphens only)
-- For action="add": send the job inside "job", "message" is required and "schedule" is required
-- For action="update", send changes inside "patch"
-- Default: jobs run as isolated agent turns with the specified message
-- Before creating or updating a scheduled job, call the datetime tool first to get the precise current time and unix_ms timestamp. Do NOT guess or estimate timestamps.
-- Use "jobId" as the canonical identifier; "id" is accepted for compatibility.`
+	4) update
+	{
+	"action": "update",
+	"jobId": "string",              // required
+	"patch": {
+		"name": "string",             // optional
+		"schedule": { ... },          // optional
+		"message": "string",          // optional
+		"deliver": true|false,        // optional
+		"channel": "string",          // optional
+		"to": "string",               // optional
+		"agentId": "string",          // optional
+		"deleteAfterRun": true|false, // optional
+		"disabled": true|false        // optional
+	}
+	}
+
+	5) remove
+	{
+	"action": "remove",
+	"jobId": "string"
+	}
+
+	6) run
+	{
+	"action": "run",
+	"jobId": "string"
+	}
+
+	7) runs
+	{
+	"action": "runs",
+	"jobId": "string"
+	}
+
+	SCHEDULE SCHEMA:
+
+	- at:
+	{ "kind": "at", "atMs": <unix-milliseconds> }
+
+	- every:
+	{ "kind": "every", "everyMs": <interval-ms> }
+
+	- cron:
+	{ "kind": "cron", "expr": "<5-field cron expression>", "tz": "<optional IANA timezone>" }
+
+	RULES:
+	- For action="add", send the job inside "job". Do not place job fields at the root level.
+	- For action="update", send changes inside "patch". Do not place patch fields at the root level.
+	- Always use "jobId". Do not use "id" unless explicitly required by older compatibility code.
+	- "name", "schedule", and "message" are required for add.
+	- "name" must match: lowercase letters, numbers, hyphens only.
+	- Before creating or updating a scheduled job, call the datetime tool first to get the precise current time and unix_ms timestamp. Never guess timestamps.
+	- Omit optional fields when unknown; do not invent placeholder values like "", 0, or null unless required.
+	- Jobs run as isolated agent turns using the provided "message".`
 }
 
 func (t *CronTool) Parameters() map[string]any {