diff --git a/docs/tools/scheduling.md b/docs/tools/scheduling.md
index 325b5c64..9d92a2ca 100644
--- a/docs/tools/scheduling.md
+++ b/docs/tools/scheduling.md
@@ -26,9 +26,12 @@ audit.
 Partial-update a schedule. Pass only the fields to change; absent
 fields are left alone. `targets_add` / `targets_remove` mutate the
 recipient list in the same transaction — re-adding a previously
-cancelled target drops its tombstone and starts fresh. Clearing
-`interval_seconds` to null flips recurring → one-shot. Refuses
-cancelled rows (terminal state).
+cancelled target drops its tombstone and starts fresh.
+`interval_seconds` accepts positive values only via this tool (omit
+to keep the existing cadence; pass a new positive value to change
+it). Toggling recurring → one-shot (clearing the interval) is
+operator-only via the dashboard PATCH endpoint. Refuses cancelled
+rows (terminal state).
 
 ### `cancel_schedule(id, targets?)`