--- source: 'https://howaiworks.ai/blog/claude-opus-5-announcement-2026' section: blog title: 'Claude Opus 5: Near-Fable Intelligence at Half the Price' description: >- Anthropic released Claude Opus 5 on July 24, 2026 at $5/$25 per million tokens — thinking on by default, 26% fewer tokens than Opus 4.8. date: '2026-07-24' author: HowAIWorks Team tags: - Anthropic - Claude - AI Models - LLM - AI Agents - AI Coding - AI News newsSource: Anthropic breakingNews: true readingTime: 5 minutes isReviewed: false --- # Claude Opus 5: Near-Fable Intelligence at Half the Price > Anthropic released Claude Opus 5 on July 24, 2026 at $5/$25 per million tokens — thinking on by default, 26% fewer tokens than Opus 4.8. ## Introduction Anthropic released **[Claude Opus 5](https://howaiworks.ai/models/claude-opus)** on July 24, 2026, positioning it as "a thoughtful and proactive model that comes close to the frontier intelligence of [Claude Fable 5](https://howaiworks.ai/models/claude-fable) at half the price." It ships at $5 per million input tokens and $25 per million output tokens — the same list price as Opus 4.8 — and was available on all platforms on launch day, including the Claude API, Claude apps, Claude Code, and Claude Cowork. The API model ID is `claude-opus-5`. Anthropic's documentation now names it the recommended starting point for complex agentic coding and enterprise work, the role Opus 4.8 held since May. ## What Anthropic Published The launch post frames most of its results as comparisons rather than absolute scores: - **Frontier-Bench v0.1** — surpasses all other models and "more than doubles Opus 4.8's performance at a lower cost per task." - **CursorBench 3.2** (max effort) — within 0.5% of Fable 5's peak score at half the cost. - **ARC-AGI 3** — a score "three times as high as the next-best model." - **OSWorld 2.0** — surpasses Fable 5's best result "at just over a third of the cost." - **Zapier AutomationBench** — pass rate around 1.5× the next-best model for the same cost per task. - **Scientific work** — 10.2 percentage points higher than Opus 4.8 on organic chemistry tasks and 7.7 points higher on protein tasks. Anthropic also claims Opus 5 uses **26% fewer tokens on average** than Opus 4.8, which matters more than the sticker price on agentic workloads where output volume dominates the bill. Note what these are and are not. Anthropic chose the [benchmarks](https://howaiworks.ai/glossary/benchmark), the harnesses and the effort levels, and the launch post publishes no per-benchmark score table as text. Several of the most striking figures in the announcement — Box's 8% improvement, Goldman Sachs' trading benchmark using "a seventh of the reasoning tokens," Perplexity's "nearly double Opus 4.8" on first-turn redlines — come from customers' internal evaluations, not from Anthropic's own measurements. The [system card](https://www-cdn.anthropic.com/c5fbac3f0b1280a933ebd26d3cb8bb9f5bdeaf48/Claude%20Opus%205%20System%20Card.pdf), published the same day, carries the full safety and capability evaluation. ## What Changes for Developers Opus 5 keeps the Opus 4.7/4.8 request surface — no `temperature`, `top_p` or `top_k`, no `budget_tokens`, no last-assistant-turn prefills — but two defaults changed, and one of them is a hard error: **Adaptive thinking is now on by default.** On Opus 4.8, a request that omitted the `thinking` field ran without thinking. On Opus 5 the same request runs with adaptive thinking. Since `max_tokens` caps total output — thinking plus visible text — workloads that ran thinking-off by omission need their `max_tokens` revisited. **Disabling thinking is capped at `high` effort.** `thinking: {"type": "disabled"}` combined with an effort level of `xhigh` or `max` returns a 400 error. Either re-enable thinking or step effort down to `high` or below. Three smaller changes are worth picking up: - The **minimum cacheable prompt** drops from 1,024 tokens to 512, so shorter prefixes can now create [prompt cache](https://howaiworks.ai/glossary/prompt-caching) entries with no code change. - **Mid-conversation tool changes** (beta, header `mid-conversation-tool-changes-2026-07-01`) let you add or remove tools between turns without invalidating cache hits on earlier turns. - **Automatic fallbacks** (beta, header `server-side-fallback-2026-07-01`) accept `fallbacks: "default"`, which picks a recommended fallback model based on the refusal category rather than making you name one. Two capabilities present on Opus 4.8 are missing: **Priority Tier is not supported** on Opus 5, and the server-side web fetch tool is not available. Teams with a Priority Tier commitment need to plan capacity separately. The specifications otherwise carry over: a 1M-token [context window](https://howaiworks.ai/glossary/context-window) at standard pricing, 128K max output per request (300K on the Message Batches API with the `output-300k-2026-03-24` beta header), and `effort` defaulting to `high` on the Claude API and [Claude Code](https://howaiworks.ai/ai-tools/claude-code). The knowledge cutoff moves forward to **May 2026**, four months later than Opus 4.8's January 2026. ## Behavior and Prompt Re-Tuning Anthropic's migration guidance is unusually specific about what to *remove* from existing prompts: - **Delete carried-over verification instructions.** Opus 5 verifies its own work without being told to, and leaving "double-check your work" scaffolding in place causes over-verification. - **Prompt explicitly for length.** Default visible responses and written deliverables run longer than on Opus 4.8, and lowering `effort` reduces thinking volume without reliably shortening the visible answer. - **Constrain scope and subagents.** For narrow tasks, say so explicitly; in multi-agent frameworks, give guidance on when delegation is warranted or cap the number of subagents. - **Re-run your effort sweep.** Anthropic says `low` and `medium` are stronger on Opus 5 than on earlier Opus models and are worth testing as cost controls, while `max` is worth testing where capability matters more than token spend. ## Safety Posture Anthropic describes Opus 5 as its "most aligned model to date," reporting the lowest rates of deceptive behavior it has measured and a score of 2.3 on overall misaligned behavior in its automated behavioral audit. It also reports that safety classifiers intervene 85% less often than on Fable 5 — and that biology-related requests blocked on Fable 5 now route to Opus 5 rather than Opus 4.8. The cybersecurity safeguards are drawn narrowly rather than broadly: vulnerability finding in source code is allowed, while binary-based scanning, penetration testing and exploit generation are blocked. Enterprises whose legitimate work falls inside those blocks can apply to the Cyber Verification Program. Anthropic is explicit that Opus 5 remains behind Claude Mythos 5 on both offensive cybersecurity and biology research. ## Conclusion Opus 5's pitch is not a new capability ceiling — Fable 5 still holds that — but a better price-performance point at the tier most production workloads actually run on. The 26% token reduction and the near-Fable results at half Fable's price are the claims worth validating first on your own evaluation set, because they are the ones that change a budget. The migration itself is small: swap the model ID, audit any request that disables thinking, and re-check `max_tokens` on workloads that were implicitly running thinking-off. The larger job is prompt hygiene — the instructions you added to make Opus 4.8 verify itself and stay brief now work against you. ## Sources - [Introducing Claude Opus 5](https://www.anthropic.com/news/claude-opus-5) — Anthropic's launch announcement, July 24, 2026 - [Claude Opus 5 System Card](https://www-cdn.anthropic.com/c5fbac3f0b1280a933ebd26d3cb8bb9f5bdeaf48/Claude%20Opus%205%20System%20Card.pdf) — safety and capability evaluation - [Models overview](https://platform.claude.com/docs/en/about-claude/models/overview) — specifications and pricing for all current Claude models - [Migrating to Claude Opus 5](https://platform.claude.com/docs/en/about-claude/models/migration-guide) — breaking changes and the migration checklist ## Frequently Asked Questions ### When was Claude Opus 5 released? Anthropic announced Claude Opus 5 on July 24, 2026. It was available on the Claude API, Claude apps, Claude Code, and Claude Cowork on day one. ### How much does Claude Opus 5 cost? $5 per million input tokens and $25 per million output tokens — the same list price as Claude Opus 4.8, and half the price of Claude Fable 5. Fast mode costs twice the base rate. ### What is the model ID for Claude Opus 5? The Claude API model ID is `claude-opus-5`, with no date suffix. On Amazon Bedrock it takes an `anthropic.` prefix; on Google Cloud the bare ID is used. ### What changes when migrating from Claude Opus 4.8 to Claude Opus 5? Adaptive thinking is now on by default when the `thinking` parameter is omitted, and disabling thinking is only allowed at effort `high` or below — combining `thinking: {"type": "disabled"}` with `xhigh` or `max` returns a 400 error. Everything else is a model-ID swap plus prompt re-tuning. ### Is Claude Opus 5 more capable than Claude Fable 5? No. Anthropic positions Opus 5 as coming close to Fable 5's frontier intelligence at half the price, and still names Fable 5 as its most capable widely released model. Opus 5 is now the recommended default for complex agentic coding and enterprise work. --- Source: https://howaiworks.ai/blog/claude-opus-5-announcement-2026 — HowAIWorks.ai