A small model can make routine work affordable. A migration still needs a test of the requests your application actually sends.
The launch and the price boundary
Anthropic released Claude Haiku 5.5 on October 7, 2026. The model targets bounded, high-volume work such as classification and summaries. Its Claude Platform identifier is claude-haiku-5-5.
For prompts up to 100,000 tokens, Anthropic lists $0.10 per million input tokens and $0.50 per million output tokens. Above that prompt threshold, the listed rates are $0.50 and $2.50. Cache reads cost $0.01 or $0.05 per million tokens, respectively.
The lower tier is useful for short requests. A long document can move the request into a different cost estimate. Check the actual prompt length before choosing a rate.
Recount tokens before estimating savings
The migration documentation describes a changed tokenizer. Equivalent text can use more tokens than on Haiku 4.5. Reusing an old token count can therefore misstate cost and output limits.
For a support classifier, I would start with a fixed set of reviewed tickets. Include ambiguous examples that should go to a person. Count wrong classifications and unnecessary escalations separately. A cheaper answer only helps if the workflow accepts it.
Check request compatibility
Anthropic documents changes to thinking configuration, sampling parameters, and assistant prefill. Legacy thinking budgets need migration. Review the documentation for your provider before copying settings between endpoints.
- Recount representative prompts with the new model.
- Review thinking and sampling settings against the migration guide.
- Test output parsing and token limits on real responses.
- Replay reviewed tasks before routing live traffic.
- Keep human review and a working rollback route.
Haiku versus Sonnet: compare accepted-task cost
Anthropic’s October 7 price table lists Sonnet 5.5 at $2 per million input tokens and $10 per million output tokens. Its cache-read rate is $0.10. Haiku’s lower prompt tier costs $0.10 for input, $0.50 for output and $0.01 for cache reads.
For an illustrative batch of short requests totaling 1 million input tokens and 200,000 output tokens, Haiku’s uncached token cost is $0.20. Sonnet’s is $4. This arithmetic assumes every Haiku prompt stays within the lower tier. It excludes cache writes, retries, tools and other service charges. Equal billable token totals do not mean that the same text produces equal token counts.
Use that example to plan a test, not to claim a 20-fold saving on your workload. Try Haiku on bounded classifications or summaries with reviewed answers. Compare Sonnet on tasks where Haiku misses your acceptance rules. Include correction time and rejected results in the cost per usable answer. We have not run an independent comparison of these models.
Measure accepted work
Track the full cost of each accepted task, including retries and review. Keep effort settings fixed during a comparison. Then test whether a lower setting still meets your acceptance rules. This is a proposed evaluation procedure, not a MustHave.ai benchmark.
Our agent cost-control guide covers spending limits. The Sonnet 5.5 guide covers the larger model and its updated cache-read price.
Choose a bounded first task
I would migrate one repeatable task first and retain the previous route until reviewed results justify the switch. Which routine task has clear enough acceptance rules for your first trial?
