Claude Opus 5.5 против Opus 5 против Fable 5.1: реальные тесты

Anthropic’s current Claude lineup makes a simple price comparison misleading. This review puts Claude Opus 5.5, Claude Opus 5, and Claude Fable 5.1 through the same five prompts and reports the task result, local elapsed time, route-reported token usage, and the limits of each observation.

The practical difference is visible in the task cards. Opus 5.5 was the quickest and cheapest on the measured pack, Fable 5.1 produced the fewest output tokens and the cleanest Chinese-format response, and Opus 5 took the most time, while Opus 5.5 used the most output tokens. The coding card adds an important qualification: shorter output was not automatically better output.

We copied the five prompts from the earlier Claude Opus 5.5 review and ran every prompt once for each model. The request settings were identical: an 8,192-token ceiling, high effort, one user message, and no tools. The route returned HTTP 200 and end_turn for all 15 requests.

What the three models cost and expose

The three APIs share a 1M-token context window and a 128K maximum output in Anthropic’s current model documentation. Their billing units and status differ: Opus 5.5 is the latest Opus route, Opus 5 is marked legacy, and Fable 5.1 carries the highest standard input/output rate.

For a simple non-cached example, 100,000 input tokens plus 20,000 output tokens costs $0.80 on Opus 5.5, $1.00 on Opus 5, and $2.00 on Fable 5.1 at the listed rates. Fable 5.1 has a lower cache-read rate than Opus 5, so cache-heavy agent workloads need a separate calculation.

What the official benchmark table shows

Anthropic Claude Opus 5.5 announcement places all three models in the same provider comparison table. Opus 5.5 leads the listed rows, but these are provider-reported results with benchmark-specific harnesses and effort settings. The announcement itself warns that narrow benchmark margins are a less reliable guide to real-world differences at this capability level.

The table is useful for locating the provider’s claimed performance frontier. It is not a replacement for the matched cards below: our test uses short single-turn prompts, high effort, no tools, and a third-party controlled route.

Same prompts, same request settings

We copied the five prompts from the earlier Opus 5.5 test pack and sent each one once to each model. The client rotated model order by task, used UTF-8 JSON, and measured from request start until the complete response body was read. All 15 requests returned HTTP 200 and end_turn. For the broader rationale and repeatable workflow, see How GlobalGPT tests AI models.

Time and token comparison

*Estimate from route-reported input/output tokens and Anthropic’s listed standard API rates. It excludes cache charges, platform credits, taxes, and markup. Elapsed time is local end-to-end wall time after the request was sent, not provider latency or tokens per second. “Thinking” is a route-reported usage field, not independently measured hidden reasoning.

The aggregate points in different directions depending on the metric. Opus 5.5 returned the fastest total and the lowest estimated cost, Fable 5.1 returned the fewest output tokens, and Opus 5 had the slowest total in this pack. A shorter answer is not automatically a better answer: the coding card shows why output content and edge-case handling still need to be read.

Five matched task cards

Особенности API и миграции

Opus 5.5 is not a drop-in rename for every Opus 5 integration. Anthropic’s migration guide says thinking cannot be disabled on Opus 5.5; requests that try to disable or manually enable the old thinking mode return a 400 error. The migration also changes forced tool use, ties thinking blocks to the model and conversation, and replaces the older computer-use tool on the Claude API and Google Cloud path.

The shared test used output_config.effort: high for all three models so the prompt results were easier to compare. That means these runs do not reproduce each model’s default effort setting. Fable 5.1 is documented with adaptive thinking always on and high default effort; Opus 5.5 is documented with adaptive thinking always on and medium default effort; Opus 5 uses adaptive thinking with high default effort.

What this test actually supports

If you want to reproduce the comparison without opening three separate accounts, try the model comparison workflow in GlobalGPT. The direct model route and the upstream provider mapping should still be verified separately for any production decision.

ЧАСТО ЗАДАВАЕМЫЕ ВОПРОСЫ

Which model was fastest in the matched test?

Claude Opus 5.5 had the lowest total local elapsed time: 47.725 seconds across five sequential requests. This is a route observation, not provider-side latency.

Which model used the fewest output tokens?

Claude Fable 5.1 used 2,690 route-reported output tokens across the five tasks, compared with 3,709 for Opus 5 and 3,952 for Opus 5.5.

Which model was cheapest in the test?

Using official standard API rates and the returned input/output token counts, Opus 5.5 produced the lowest five-run estimate at $0.0818. This excludes cache, credits, taxes, and platform markup.

Did all three models pass the same tasks?

All three returned grounded five-bullet extraction, parseable JSON with the requested keys, and the correct total of 67. The coding and Chinese-format cards show meaningful output differences.

Was this a long-context benchmark?

No. The reused extraction prompt contains a short passage. It tests grounding and exact formatting, so it should not be presented as evidence of million-token context performance.

Is Claude Opus 5 still current?

Anthropic’s model docs label Opus 5 as active but legacy and recommend considering Opus 5.5 for improved performance. Existing API integrations should review the migration guide before switching.

Official specifications: Opus 5.5 docs, Opus 5 docs, и Fable 5.1 docs. Provider benchmark values are attributed to Anthropic; hands-on values come from the matched test pack described above.