New cost: **$0.328004**. Cumulative study cost: **$1.521706** (includes original failed Opus attempt).

Usage: 53,091 input, 5,782 output, including 0 reasoning tokens.

# Opus 5.5 completion with structured output

Completed 18/18 planned calls; 18/18 controls passed. Median latency 3.63s; mean 3.97s. Observed cost extrapolates to $18.222 per 1,000 judgments.

## Repair and comparison boundary

The original JSON-object run stopped after 2 calls when Azure returned Markdown-fenced JSON. Its raw response and $0.02914 charge remain preserved. This new arm requests strict json_schema, using the identical schema already present in the frozen system prompt. It starts with empty-r1, the failed case, as its first real canary. It counts that successful canary among its 18 calls. No output stripping, repair, automatic retry, prompt change, or scorer change was applied. This completes coverage under the revised output contract; it does not fill or overwrite the original JSON-object arm.

[OpenRouter structured-output documentation](https://openrouter.ai/docs/guides/features/structured-outputs) documents json_schema and require_parameters. The observed repair passed here; native enforcement and the root cause of the prior route failure are not independently established.

## Settings and pricing

Model: anthropic/claude-opus-5.5. Providers observed: Azure. Thinking: low requested, minimum advertised; Azure reported zero reasoning tokens, which does not prove thinking was disabled. Output cap: 2,048. Three rounds of six benign controls, serial, 90s per call, 25-minute model ceiling, $5 conservative reservation cap, zero automatic retries, stop on first operational failure. toolCalls/maxToolCalls: 0/0.

Catalog USD/million tokens: input $4.00; cached input $0.20; output $20.00. Raw provider cost and catalog snapshot preserved; no missing cost treated as zero.

| Case | Passed / attempted |
|---|---:|
| grounded | 3/3 |
| empty | 3/3 |
| fabricated | 3/3 |
| clarification | 3/3 |
| dependency | 3/3 |
| missing-task | 3/3 |

| Round | Passed / attempted |
|---|---:|
| 1 | 6/6 |
| 2 | 6/6 |
| 3 | 6/6 |

## Validation and interpretation

Dry-run, typecheck, and 3/3 focused rubric tests passed. verify.mjs checks frozen input hashes, requested/effective model identity, low thinking, strict schema request, positive usage, unique generations, and raw cost reconciliation. Independent live calls use benign synthetic evidence with no targets, tools, or product agent execution. Six controls repeated three times are not 18 independent cases or broad accuracy proof. Earlier model scores used JSON-object mode, so the output-contract change is a comparison limitation.

[Full comparison and original Opus failure](../benign-judge-anthropic-20260923/report.md).