Optional human-readable description of the rule's purpose. PATCH semantics: omit the field to leave the persisted value unchanged; pass explicit JSON null to clear a previously-set description; pass a string to set it.

Optional customer-authored template shown to the AI agent when this rule blocks or warns on a request. The server stores and serves this string as-is — it is never interpolated server-side; the local budget-gate client renders the following template variables before display: {model}, {spent}, {limit}, {window}, {percentUsed}, {ruleName}. Only the developer/policy text is customer-authored — the action directive shown alongside it is composed by the client, not this field. PATCH semantics: omit the field to leave the persisted value unchanged; pass explicit JSON null to clear a previously-set message; pass a string to set it.

Optional soft threshold that triggers a warning without blocking. Unit matches hardLimit: dollars for TOTAL_COST, whole counts for token/error metrics. PATCH semantics: omit the field to leave the persisted value unchanged; pass explicit JSON null to clear a previously-set threshold; pass a numeric value to set it.

Hard enforcement threshold in the metric's native unit: dollars for metricType=TOTAL_COST (e.g. 10 = $10/window), or a whole count for metricType=TOKEN_COUNT / ERROR_COUNT / etc. When crossed and the rule is not in shadow mode, the declared action is executed. PATCH semantics: omit the field to leave the persisted value unchanged; pass explicit JSON null to clear a previously-set limit; pass a numeric value to set it.

Optional dimension to partition the rule evaluation (per-model, per-provider, etc.). PATCH semantics: omit the field to leave the persisted value unchanged; pass explicit JSON null to clear a previously-set dimension; pass an enum value to set it.