Sonnet and Opus task-cost comparisons
Read how Anthropic varies effort in its comparisons. The results are specific to the tasks and configurations tested.
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Routing, fallbacks, and model portfolios
Use task-aware model routing and approved fallbacks to balance quality, latency, resilience, and cost.
Plain-English definition
Model routing sends different requests to different approved models or deployments based on task, risk, context, latency, or capacity. A model portfolio is the set of primary, fallback, and specialized options plus the policy that chooses among them.
Memory trick: A portfolio is a policy, not a pile of models.
Why it matters
One model rarely dominates every task and operating condition. Routing can use a smaller model for simple work and reserve a stronger model for difficult or high-risk cases, but the policy must be evaluated for quality, fairness, availability, and cost.
Simple example
A support system routes short classification requests to a smaller model, sends ambiguous or policy-sensitive cases to a stronger model, and falls back to a queued human review when both are unavailable. The routing decision is logged and tested like any other product behavior.
Example figures are illustrative calculations, not current quoted market prices.
Current example
Route by the task: Sonnet 5.5 and Opus 5.5
Anthropic describes Sonnet 5.5 as a faster complement to Opus 5.5. Its launch discussion also shows that raising Sonnet’s effort can bring cost per task closer to Opus on some evaluations. A sensible portfolio therefore needs measured task categories and effort limits. Routing every request to a lower-priced model, then repeatedly escalating failures, can spend more than selecting the right model at the start.
GPT-6.1 Sol and premium fallback cost
Work through why a failed low-cost attempt followed by an Astra call must be counted together.
Release evidence reviewed and recorded Oct 6, 2026. Test your routing policy against a single-model baseline. Log the initial model, effort, escalation reason, and full task cost; vendor benchmark charts do not establish your portfolio’s savings.
Common mistake
Token price alone is a poor routing policy. A cheaper model that produces more retries or unsafe escalations may have a higher cost per successful outcome.
Practical takeaway
What you can do with this
Define routing rules, confidence or task signals, fallback order, capacity limits, and audit metrics. Compare the portfolio with a single-model baseline.
Decision check: can the portfolio explain why each request went to a model and what happens when that option is unavailable?
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Step 45 of 48: Routing, fallbacks, and model portfolios