New inference cost: **$0.648720**; cumulative study cost: **$1.193702**. BYOK upstream charges are included where applicable. No missing costs are treated as zero.

New usage: 33,183 input and 7,212 output tokens, including 741 reasoning tokens.


**Completed follow-up:** [Opus strict-schema run](../benign-judge-opus-schema-20260923/report.md) passed 18/18 at low requested thinking, median 3.63s, new cost $0.328004. Cumulative study cost including this follow-up: $1.521706. The original JSON-object failure below is preserved; the follow-up changes the output contract and reports zero reasoning tokens.

## Historical run-blocking findings

**Opus 5.5 / Azure:** empty-r1 returned Markdown-fenced JSON despite the requested json_object mode. The run stopped after two calls; 16 calls remain unattempted. The original response and charge are retained, and no fence stripping or output repair was used. This establishes a route/output-contract failure, not poor substantive judging.

[Anthropic structured-output documentation](https://platform.claude.com/docs/en/build-with-claude/structured-outputs) and [OpenRouter structured-output documentation](https://openrouter.ai/docs/guides/features/structured-outputs) describe schema-constrained JSON. The separately labeled json_schema follow-up linked above now completes all 18 calls. It does not replace this frozen json_object comparison; the prior failure root cause remains unverified.

# Fable 5.1 and Opus 5.5 judge calibration

Both models require thinking and were requested at low, their minimum advertised setting. Six frozen benign controls × three planned rounds, 2,048 output-token cap, JSON-object mode, zero automatic retries, toolCalls/maxToolCalls = 0/0. No product agent, target, or tool execution occurred.

**Stopped anthropic/claude-opus-5.5 after 2 calls:** Unexpected token '`', "```json
{""... is not valid JSON. 16 calls remain unattempted; raw failure is preserved.

| Added judge | Thinking | Passed / attempted | Median seconds | Run cost | Cost / 1,000 judgments* |
|---|---|---:|---:|---:|---:|
| anthropic/claude-fable-5.1 | low | 18/18 | 7.17 | $0.619580 | $34.421 |
| anthropic/claude-opus-5.5 | low | 1/2 | 4.49 | $0.029140 | $14.570 |

*Extrapolated from observed calls, including invalid judgments. Six synthetic controls do not establish broad judge accuracy; three repeats are not 18 independent cases.

## Pricing at admission

USD per million tokens; each catalog snapshot is preserved. Output prices also apply to reasoning tokens.

| Model | Input | Cached input | Output |
|---|---:|---:|---:|
| anthropic/claude-fable-5.1 | $10.00 | $0.25 | $50.00 |
| anthropic/claude-opus-5.5 | $4.00 | $0.20 | $20.00 |

[Anthropic effort controls](https://platform.claude.com/docs/en/build-with-claude/effort) and [OpenRouter live catalog](https://openrouter.ai/api/v1/models). Requested options and raw usage are retained; provider internals are not claimed verified.

## Case results

| Model | Grounded | Empty | Fabricated | Clarification | Dependency | Missing task |
|---|---:|---:|---:|---:|---:|---:|
| anthropic/claude-fable-5.1 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
| anthropic/claude-opus-5.5 | 1/1 | 0/1 | 0/0 | 0/0 | 0/0 | 0/0 |

## Extended comparison

Earlier runs retain their original dates, request settings, failures, and prices. Incomplete runs have different case coverage and must not be ranked by their aggregate fractions. FlashX attempts are shown separately.

| Model/run | Thinking | Passed / attempted | Median seconds | Cost / 1,000 judgments* |
|---|---|---:|---:|---:|
| openai/gpt-6-luna | none | 13/18 | 2.22 | $0.194 |
| google/gemini-3.8-flash | low | 15/18 | 3.41 | $1.686 |
| google/gemini-3.5-flash-lite | minimal | 12/18 | 1.22 | $0.958 |
| deepseek/deepseek-v4.1-flash | none | 15/18 | 1.48 | $0.273 |
| z-ai/glm-5.3-flash | low | 12/18 | 1.54 | $0.253 |
| z-ai/glm-5.3-flashx | low | 5/9 | 2.59 | $0.453 |
| openai/gpt-6-astra | low | 18/18 | 6.34 | $22.414 |
| openai/gpt-6-sol | none | 18/18 | 2.93 | $3.737 |
| z-ai/glm-5.3 | low | 5/6 | 2.12 | $1.216 |
| z-ai/glm-5.3-flashx (fresh replication) | low | 3/5 | 2.55 | $0.394 |
| anthropic/claude-fable-5.1 | low | 18/18 | 7.17 | $34.421 |
| anthropic/claude-opus-5.5 | low | 1/2 | 4.49 | $14.570 |
| anthropic/claude-opus-5.5 (strict-schema follow-up) | low requested | 18/18 | 3.63 | $18.222 |

## Validation and limits

The rubric, case, and exact request hashes were checked against preserved inputs; verification.json records model identity, positive usage, generation uniqueness, thinking settings, and cost reconciliation. Typecheck and focused rubric tests passed (3/3). Expected labels were not sent to judges; no prompt tuning or output repair was applied. The first transport, schema, identity, or accounting error stops that model; schema-valid rubric errors remain failed calibration outcomes. No production-judge promotion is claimed. GPT-6 Terra remains pending per user instruction.

[Original panel and Astra/Sol extension](../benign-judge-comparison-v2-20260922/report.md). [Full GLM-5.3 and FlashX replication](../benign-judge-glm53-followup-20260922/report.md).