# When an alert fires

**In short:** every watch gets its own alert rules from its own history, so a busy watch and a quiet one are each judged by their own normal. Add your own on a watch's page in the app (**Add a rule**): a limit, such as "below 10 in 24 hours", or a change, such as "3 times the usual". A rule you set is never changed for you.

Each watch gets its own automatic rules, picked from its own history, so a busy watch and a quiet one are judged differently: up to the plan's automatic rules per watch (Free 2, Pro 4). A rule is written in **times usual**: `1H ×4` fires when the last hour is 4 times its usual level; `24H ×0.3` when a day falls to 30% of usual. Automatic rules can change as CountWatch learns a watch. When no rule fits a watch, the import result says so and suggests a fixed limit.

**Your own rules.** `POST /v1/rules` sets a rule for a metric (all its watches, now and later) or one watch (its spike, drop or limit rules override the metric's of the same kind): a change `{direction, hours, times_usual}` replaces the automatic rules of its direction, a fixed limit `{bound: max | min, hours, limit}` is added. A rule you set is never changed automatically; the answer estimates how often a watch rule would have alerted. `GET /v1/rules?watch_id=` shows every rule in force; `DELETE /v1/rules/{rule_id}` goes back to automatic.