Claude Haiku 5.5 is a candidate for high-volume work where cost and response time matter, but a small model should earn its place through tasks you can verify. It should not inherit the authority of a larger agent simply because its token price is lower.
Anthropic announced Haiku 5.5 on October 7, 2026. This guide separates the published offer from our suggested evaluation method. We have not benchmarked Haiku 5.5 on an Agent.Space workload. Official model page.
Read the pricing condition, not only the lowest number
The official page lists two prompt-length bands for the Claude Platform:
These published rates were checked October 10, 2026. They are not a monthly subscription price or an Agent.Space quote. Other billing categories and provider terms need their own checks. Do not apply the lower band to an arbitrarily long agent conversation.
For a deliberately simplified short-prompt example, 20,000 uncached input tokens and 2,000 output tokens cost $0.003 at the lower rates, excluding every other charge. A separate request with 120,000 uncached input tokens and 2,000 output tokens falls in the higher band and costs $0.065 under these assumptions. Check the actual prompt length and reported usage rather than applying the lower rate to every request.
The coding-agent API cost guide explains how to count repeated requests, tools, caching, and retries at task level.
Give it work with a clear correctness test
Our first experiments would be bounded tasks: classify a supplied issue, extract fields from a known format, summarize a small diff, or propose a localized edit with an existing test. These are evaluation suggestions, not established performance results.
Define the acceptance rule before looking at the answer. For extraction, compare the fields against a labeled example. For a patch, rerun the reproduction and inspect unrelated changes. For a summary, verify that it preserves the decisions and caveats that matter.
A fast, plausible answer is a weak signal when no one knows what it must get right.
Escalate ambiguity, not merely task length
Keep a stronger model in the evaluation when requirements conflict, the evidence spans several systems, or the consequences of a plausible mistake are high. That does not establish a universal model ranking; it tells you where the evaluation must be harder.
The Opus 5.5 versus Sonnet 5.5 guide provides a decision framework for those alternatives. You can use different models for different tasks without allowing a low-cost stage to approve a high-impact action.
For example, a small model can suggest which files need review. A missed file must not become an automatic declaration that the change is safe. Keep the final acceptance evidence independent of the routing suggestion.
Compare complete workflows, not isolated benchmark scores
Use independent copies of the same task, the same tools, and a fixed stop condition. Record accepted results, failed attempts, total usage, and reviewer effort. Repeat across several representative cases before choosing a default.
If you cite a benchmark, preserve its dataset, harness, settings, and who ran it. Do not blend different test setups into a single “best coding model” claim. The model-selection checklist helps structure that comparison.
Verify availability on the route you will use
Anthropic's release and its official Claude Code availability do not prove that every gateway or managed workspace has enabled Haiku 5.5. Confirm the exact model in the current provider catalog and client.
For Agent.Space, check live pricing and availability and the supported harness/model selector before planning a workflow around it. If the route is available and fits the task, start a small workspace experiment. Keep the result and usage evidence; a lower advertised rate is a reason to test, not a reason to skip review.