SHELFCRITTER AI Digest

MODEL

Claude Opus 5

modeltopic-noteanthropic

Overview

Claude Opus 5 is Anthropic‘s frontier-adjacent Opus-tier model shipped July 24, 2026, positioned as a near-Fable 5 intelligence tier at unchanged Opus pricing. Standard rates hold at $5 / $25 per M input/output tokens — identical to Claude Opus 4.8, not a discount — with fast mode at $10 / $50. 1M-token context window. Opus 5 takes the top two spots on Artificial Analysis GDPval-AA v2 (ELO 1861 xhigh, 1827 lower-effort), scores 42/42 on IMO 2026, and posts 30.16% on ARC-AGI-3 at high effort (~4× the prior leaderboard leader). Anthropic’s system card cites Gray Swan’s indirect-prompt-injection benchmark at 2.0% attack success (down from 5.5% on Claude Opus 4.8, vs Claude Mythos 5 at 2.6% and GPT-5.6 Sol at 20%). Ships as the default Opus in Claude Code v2.1.219 the same day.

Timeline

  • 2026-07-25-AI-Digest — Anthropic ships Claude Opus 5 on July 24 at unchanged Opus economics — $5 / $25 standard (identical to Claude Opus 4.8), $10 / $50 fast — with a 1M-context window. Opus 5 takes the top two spots on Artificial Analysis GDPval-AA v2 (ELO 1861 xhigh, 1827 lower-effort), scores 42/42 on IMO 2026, and posts 30.16% on ARC-AGI-3 at high effort (~4× the prior leaderboard leader). Anthropic’s system card cites Gray Swan’s indirect-prompt-injection benchmark at 2.0% attack success, down from 5.5% on Opus 4.8 vs Mythos 5 at 2.6% and GPT-5.6 Sol at 20% — the strongest single prompt-injection data point Anthropic has published, but one vendor-cited benchmark, not independent replication. Ships as the default Opus in Claude Code v2.1.219 the same day (claude-opus-5, 1M context), removes Claude Opus 4.7 from fast mode, and slots alongside Claude Opus 4.8 under /fast. Narrow read: the load-bearing fact is not “Opus got cheaper” — Opus tier pricing held flat. What moved is intelligence: Opus 5 approaches Fable 5 territory on public benchmarks while charging Opus 4.8 rates, giving Anthropic a $5/$25 frontier-adjacent SKU that undercuts Fable 5 on price without cannibalizing the tier structure. Structural read the corpus carries: Opus 5 lands into a market where Moonshot AI‘s Kimi K3 set a Sonnet-parity $3/$15 bar on the pricing floor while Fable 5 and GPT-5.6 Sol hold the frontier ceiling — Opus 5 targets the middle: “80% of Fable 5 at 50% of the cost” is the honest read, not “Fable 5 at half price.” Not yet on the Aider polyglot leaderboard — the top-5 today still shows gpt-5 (high) at 88.0% — so developer-workflow evals are the delayed corroboration to watch through the next 10–14 days. 30-day watch: independent prompt-injection replication (Gray Swan is one vendor-cited datapoint); Aider polyglot placement once Opus 5 is scored. 60-day watch: Opus 5 pricing durability against a Fable 5 price move or a K3-tier undercut.

Key Developments

  1. Tier-Consistent Pricing at Frontier-Adjacent Intelligence (July 24, 2026): Standard $5 / $25, fast $10 / $50 — unchanged from Claude Opus 4.8, not a discount. Opus 5 takes top-2 on Artificial Analysis GDPval-AA v2 (ELO 1861 xhigh / 1827 lower-effort), 42/42 on IMO 2026, 30.16% on ARC-AGI-3 at high effort. The disciplined framing: tier-consistent price with a stepped-up intelligence delivery, not a price war on Fable 5. Opus 5 is Anthropic’s frontier-adjacent SKU at Opus economics — approaches Fable 5 on public benchmarks while charging Opus 4.8 rates, without cannibalizing the tier structure.

  2. Gray Swan 2.0% Prompt-Injection Number as Strongest Single Data Point — But Vendor-Cited (July 24, 2026): System card cites Gray Swan’s indirect-prompt-injection benchmark at 2.0% attack success — down from 5.5% on Claude Opus 4.8, vs Claude Mythos 5 at 2.6% and GPT-5.6 Sol at 20%. Strongest single security data point Anthropic has published on this axis, but one vendor-cited benchmark — treat as directional pending third-party evaluation. Independent replication is the 30-day watch item.

  3. Default Opus in Claude Code v2.1.219, Removes Opus 4.7 from Fast Mode (July 24, 2026): Opus 5 ships as the new default Opus in Claude Code v2.1.219 (claude-opus-5, 1M context), removes Claude Opus 4.7 from fast mode, and slots alongside Claude Opus 4.8 under /fast. Same-day model-and-substrate delivery — the model release and Claude Code cutover land in the same tag, not a stagger.

See also: Anthropic, Claude Fable 5, Claude Opus 4.8, Claude Opus 4.7, Claude Code, MOC - Major Companies, MOC - Agentic Coding.