Claude Opus 5.5とは？API料金と性能、前世代からの変更点

"Claude Fable 5.1" ／ "For demanding reasoning and long-horizon agentic work" ／ "Claude Opus 5.5" ／ "For long-running agentic coding and knowledge work" ／ "Claude Sonnet 5" ／ "The best combination of speed and intelligence" — Claude Docs 料金表のモデル行より（上から料金の高い順）

"We’re introducing Claude Opus 5.5, the first model in our new Claude 5.5 family. It performs at the level of Claude Fable 5.1 on most work and costs 40% less to run than Opus 5." ／ "In addition to the price drop, we’re increasing five-hour usage limits on Pro, Max, Team, and seat-based Enterprise plans." ／ "Claude Opus 5.5 is now available on all platforms, including Amazon Web Services, Google Cloud, and Microsoft Azure." — Anthropic 公式発表の冒頭・料金の節・「Availability」節より

"On our benchmarks, Claude Opus 5.5 leads in agentic coding, computer use, and knowledge work. That said, at these levels of capability we’ve found that benchmark margins have become a less reliable guide to real-world differences. In our own use, the gap between Opus 5.5 and Claude Fable 5.1 is narrower than these scores suggest." ／ "On GDPval-AA v2.1, a test of real-world work across 44 occupations, Opus 5.5 scores 1846 Elo, ahead of Fable 5.1 and Opus 5." ／ "At max effort, Opus 5.5 scores 1846 Elo, where Fable 5.1 scores 1735 and Opus 5 scores 1708." ／ "At default effort (medium), Opus 5.5 scores 52.5%, compared to 51.8% for Fable 5.1 (max) and 46.6% for Opus 5 (max)." ／ "At default effort (medium), Opus 5.5 scores 54.6%, higher than all other models, beating GPT-6 Astra’s top score (53.3%) for about a fifth of the cost per task." — Anthropic 公式発表のベンチマークの節（GDPval-AA・CursorBench・FrontierCode）より

"Claude Fable 5.1" ／ "For demanding reasoning and long-horizon agentic work" ／ "$10" ／ "$50" ／ "On Claude Fable 5.1 and Claude Mythos 5.1, a cache hit costs 2.5% of the standard input price ($0.25 USD per million tokens)." — Claude Docs 料金表の Claude Fable 5.1 行（入力・出力）と prompt caching の節より

"Opus 5.5 requires less compute to serve than Opus 5, and its pricing reflects that. Our tests show that at default settings it will cost 40% less than Opus 5 on typical workloads. Input and output tokens are $4 and $20 per million, 20% less than Opus 5." ／ "It costs less per token than Opus 5 and uses fewer tokens per task, which nets out to a 40% drop in costs." — Anthropic 公式発表の料金の節とベンチマークの節より

"Cache reads (which make up the majority of agentic and coding work costs) are $0.20 per million tokens, 60% less than Opus 5." — Anthropic 公式発表の料金の節より

"The input price falls, and the read rate falls with it, from a tenth of the input price to a twentieth." ／ "A session that is mostly cache reads can save up to 60% on input. A short question with no cache and a long answer can save up to 20%, because output dominates it. Most Claude Code tasks sit between the two." ／ "Writing to the cache costs more than a fresh read, at 1.25 times the input price for a five-minute cache and twice the input price for a one-hour cache, on today's pricing." — Claude 公式ブログより

"We’re also providing subscription users a rate limit reset, which you can now save and use whenever you choose." — Anthropic 公式発表の料金の節より

"On a Pro, Max or Team plan, the lower Opus 5.5 price is passed on to your limits, including cached context, so they go about 25% further than on Opus 5. The extra cut on cache reads is an API price change." — Claude 公式ブログより

"Four breaking changes affect code already running on Claude Opus 5:" ／ "thinking can't be disabled" ／ "forced tool use returns an error" ／ "thinking blocks are tied to the model and the conversation" ／ "The first three also apply on Claude Fable 5.1." ／ "it enforces that check by default for accounts created on or after August 31, 2026, 00:00 UTC, on the Claude API and on cloud platforms. On those accounts, a request that replays a block after such a change returns a 400 error." — Claude Docs の冒頭と「Breaking changes」節より

""thinking.type.disabled" is not supported for this model. Use "thinking.type.adaptive" and "output_config.effort" to control thinking behavior." ／ "A request that omits effort runs at medium; on Claude Opus 5 it ran at high." ／ "At the same effort setting the model tends to think more per turn than Claude Opus 5, most of all at xhigh and max. Re-run your effort sweep rather than carrying a setting over" — Claude Docs の「Breaking changes」「Behavior differences」節より

"tool_choice: type "tool" and "any" are not supported for this model." ／ "does not support tool types: computer_20251124." ／ "On Amazon Bedrock, the earlier computer_20251124 tool continues to work on Claude Opus 5.5 as it does on Claude Opus 5, so no change is needed there." — Claude Docs の「Breaking changes」節より