Claude Fable 5

An independent benchmark and specifications recap confirms Claude Fable 5 was released on June 9, 2026, as the first Mythos-class model Anthropic has made generally available, posting state-of-the-art results across software engineering, knowledge work, scientific research, and vision benchmarks. The API model ID is cl Fable 5 is described as "Mythos made safe," with a separate classifier system monitoring every session for high-risk cybersecurity, biology, chemistry, and distillation requests and rerouting flagged requests to a category-appropriate fallback model such as Opus 4.8 for cybersecurity or Opus 5 for biology, with the use

Explainx.ai's September 2, 2026 breakdown of the September 1-2 joint release covers Claude Fable 5.1 as the generally available model and Claude Mythos 5.1 as the same weights with select safeguards lifted for vetted cybersecurity and life-sciences users via Project Glasswing. It reports headline benchmarks including T On pricing, input/output remain $10/$50 per million tokens while cache reads drop 75% from $1.00 to $0.25, yielding an estimated 25% cost reduction for typical workloads and up to 45% for highly agentic work. A new Enterprise Frontier Safeguards (EFS) feature with customer-cloud data retention is rolling out in fall 20

Anthropic's official Claude Fable product page documents the model's evolution across 2026: the June 9 launch of Claude Fable 5 (5th generation for the most ambitious work, handling days-long complex tasks), a June 12 access disruption, a July 1 access restoration, an August 6 biology-safeguards update reducing false p The page specifies Fable 5.1 availability on Pro, Max, Team, and Enterprise plans, plus the Claude Platform, AWS, Google Cloud, and Microsoft Foundry, with US-only inference available at 1.1x pricing. API pricing is $10 per million input tokens and $50 per million output tokens, with cache reads cut 75% to $0.25 per mi

This kie.ai analysis covers Claude Fable 5.1, which Anthropic officially launched on September 1, 2026 alongside Claude Mythos 5.1, positioned for coding and knowledge work. Confirmed headline pricing is reported as $10 per million input tokens and $50 per million output tokens, with cache reads falling 75% from Fable The piece functions as a retrospective on pre-launch speculation versus what actually shipped, noting that community discussion, account testing reports, and support-document sightings correctly pointed toward unchanged headline pricing and a focus on long-horizon reasoning and agent work, but were not the product docu

According to ThursdAI's July 2026 monthly recap, Claude Fable 5 returned to "full public availability worldwide on July 1 after the US export-control pause," re-establishing access for international developers after a period of restricted rollout. The same report positions Fable 5 as Anthropic's frontier-tier model for The recap contrasts Opus 5 — released at $5/$25 pricing — as landing within 0.5% of Fable 5's peak on CursorBench 3.2 at roughly half the cost per task, framing Opus 5 as a cost-effective alternative close to Fable 5 frontier intelligence. Note: these benchmark and cost-per-task claims are from a third-party podcast ro

Claude Fable 5 is a Mythos-class model from Anthropic, built for autonomous knowledge work and coding. $10 per million input tokens, $50 per million output tokens. 1,000,000 token context window, maximum output of 128,000 tokens. Higher uptime with 4 providers. Includes independent benchmarks from Artificial Analysis.

Vercel AI Gateway restores Claude Fable 5 after US lifts export controls. Updated safety classifiers may block routine coding; model fallback advised. Key takeaways for developers and businesses.

On June 9, 2026, Anthropic publicly released Claude Fable 5 as its first generally available model from a new Mythos-class tier that sits above Opus, while keeping Claude Mythos 5 restricted to approved cyberdefense and infrastructure partners via Project Glasswing. According to the Coursiv aggregator citing Anthropic Fable 5 and Mythos 5 share the same underlying model, with Fable 5 adding stricter safety classifiers in cybersecurity, biology, chemistry, and model distillation to make it safe for broad release. Adaptive thinking is always on with summarized rather than raw chain-of-thought output, and best-use framing targets auton

This third-party explainer covers Anthropic's June 9, 2026 launch of Claude Fable 5 alongside Claude Mythos 5, both positioned in a newly introduced Mythos-class tier that sits above Opus in capability. The article describes Fable 5 and Mythos 5 as Anthropic's most capable models to date, built for long-horizon agentic The article situates Claude Fable 5 within Anthropic's naming history, noting the Opus/Sonnet/Haiku structure dates to the Claude 3 generation in March 2024 and that Mythos-class is the first new capability tier added above Opus since then. It emphasizes that Fable 5 and Mythos 5 represent a qualitative rather than inc

On June 9, 2026, Anthropic made Claude Fable 5 generally available, marking the first public release from its new Mythos capability tier, according to a June 12, 2026 GMI Cloud blog post. The piece situates Fable 5 as the outcome of a deliberate post-Opus evolution rather than an incremental upgrade, describing an arc The same post frames Fable 5 against the backdrop of Anthropic's Project Glasswing safety program, noting that a Mythos Preview was limited in April 2026 to cyber defenders and critical infrastructure providers before access expanded to hundreds of organizations across 15 countries and finally reached general availabil

Towards AI's coverage describes Claude Fable 5 as Anthropic's democratized Mythos-class intelligence engine, released on June 9, 2026 at roughly 2x the price of current Opus models and less than half the price of the original Mythos Preview. It emphasizes that Fable 5 ships with a responsible safety layer on top of cap On SWE-Bench Pro, Fable 5 posts 80.3%, an 11-point lead over Anthropic's Opus 4.8 at 69.2%, with GPT-5.5 at 58.6% and Gemini 3.1 Pro at 54.2%. Towards AI positions Fable 5 as genuinely redefining what general-purpose AI can accomplish at this capability tier, though the piece is third-party commentary restating Anthrop

Labellerr's June 10, 2026 review confirms that Claude Fable 5 and Claude Mythos 5 were both released on June 9, 2026, sharing the same underlying architecture and sitting above Opus in a new "Mythos-class" tier. Fable 5 is the general-availability variant, while Mythos 5 is restricted to a small set of approved Project The article details Fable 5's three layers of safety classifiers—cybersecurity, biology and chemistry, and others—running on top of the shared base model, with internal evaluations and a 1,000+ hour external bug-bounty program reporting no universal jailbreaks. When classifiers trigger on Fable 5, responses are automat