Routing Decision Selected model: Model A Routing tier: Efficient Task complexity: Simple Primary reason: Model A satisfies the stated initial-routing requirement at the lowest cost. Fallback trigger: Validation failure, unsupported output, or policy violation. Routing Policy Simple FAQ → Model A → Validation → Escalate if validation fails Model C should not be the default because its higher unit price is not justified for this workload. The optimization target is not raw token price alone. Track cost per successfully validated response, including any fallback calls. Fallback Strategy If Model A fails validation: Escalate to Model B. Revalidate the response. Use Model C only when Model B also fails or the task requires capabilities unavailable in A/B. This creates a controlled cascade instead of sending every request to the highest-cost model. Measurement Track: Model A validation-pass rate Escalation rate Cost per successful response Average latency Policy-failure rate Do not claim savings until these metrics are measured against the current baseline.