Introducing Token Cost Control for Mastra Agents

You can now enforce spending limits with TokenCostControl — a processor that reads cumulative costs from observability data. Configure a hard maxCost cap that blocks the run when exceeded, or a soft warnAtPercent threshold that fires as usage approaches the limit.

Scopes range from a single agent run to an entire organization’s usage. Additional configuration lets you block or warn on violations, and set a lookback window that resets cost tracking after a configurable period.

Before cost control, runaway spending almost always shows up after the fact — a spike in metrics, or a bigger-than-expected bill. With TokenCostControl you can catch it in real time. The processor reads observability data before each LLM call and stops (or warns) an agent once its cumulative cost crosses a threshold.

Studio surfaces tripwires as expandable errors during development, letting you inspect the violation payload and cost breakdown in development. For production, use the onViolation callback to surface the same details.