Free tool
Agent SLO & Error Budget Calculator
Reliability targets are cheap to declare and expensive to ignore. This turns four objectives into error budgets, and error budgets into the thresholds that decide when someone gets paged.
Error budget over 30 days
60,000 tasks in the window. 3 of 3 objectives are already over budget.
Completion — budget consumed
200%
1,800 failed tasks allowed, 3,600 spent.
Hallucination escapes — budget consumed
280%
300 escapes allowed, 840 spent.
Latency — budget consumed
250%
600 slow tasks allowed, 1,500 spent.
Tool calls over budget
180,000
3.0 extra calls per task across the window.
Alerting thresholds these imply
- Page someone when the budget for any objective is burning fast enough to exhaust the window in under a day — on the completion objective, that is roughly 75 failed tasks per hour, sustained for a full day.
- Open a ticket at 50% of a budget consumed with more than half the window remaining.
- Freeze risky releases at 100%. An error budget with no consequence attached is a dashboard, not a policy.
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How this works, and what it does not cover
An error budget is the volume of failure an objective permits over a window. A 97% completion objective across 60,000 tasks permits 1,800 failures — the budget is the number, and consuming it is not a crisis until it runs out.
Three of the four objectives are ordinary reliability engineering. Hallucination escape rate is the one teams argue about, because measuring it means deciding what counts as an error that should have been caught. That argument is usually where the product improves.
The tool-call budget is a cost objective rather than a reliability one, but it belongs in the same review: a system that drifts from 12 calls per task to 15 has changed in a way that shows up on the invoice before it shows up in the dashboards.
What this does not model: correlation between objectives, seasonality, or the fact that the same underlying defect often spends two budgets at once.
The SLO starter pack: the four objective definitions, the error budget policy template, and the alerting thresholds behind the 71% to 96% programme.
If you would rather not do this yourself
Reliability Foundation — SLOs and evals in CI
Three weeks: reliability targets your team agrees on, error budgets tied to them, and evaluations that run in CI rather than in someone's head.
3 weeks · $12-18K