Discover Anthropic Claude Fable 5’s AI Innovations
On June 9, 2026, Anthropic announced the launch of its most powerful AI models to date: Claude Fable 5 and Claude Mythos 5. Representing a new “Mythos-class” tier of artificial intelligence that sits above the Opus class, these models exceed all previously available models on nearly every tested benchmark, showing exceptional advancements in software engineering, knowledge work, scientific research, and vision.
Whether you are a developer looking for an autonomous coding agent, a financial analyst processing complex data, or a cyberdefender securing critical infrastructure, here is everything you need to know about Anthropic’s groundbreaking new release.
Claude Fable 5: The New Benchmark for General AI
Claude Fable 5 is a Mythos-class model engineered specifically for general, safe use. The larger and more complex the task, the greater Fable 5’s lead becomes over past iterations.
Here are a few areas where Fable 5 is setting new industry standards:
- Software Engineering & Agentic Coding: Fable 5 can compress months of engineering work into mere days. In early testing, it successfully performed a codebase-wide migration on a 50-million-line Ruby codebase in a single day—a task that would have taken a human team over two months. It also achieved the highest score among frontier models on Cognition’s FrontierCode evaluation.
- Advanced Vision Capabilities: Fable 5 sets the new state-of-the-art standard for vision tasks. It can rebuild a web app’s source code solely from screenshots and even successfully played the video game Pokémon FireRed from start to finish using only raw visual game screenshots, without any maps or helper harnesses.
- Complex Knowledge Work: On Hebbia’s Finance Benchmark for senior-level reasoning, Fable 5 achieved the highest score of any model, and it aced trading-analysis evaluations involving root-cause and expected-value analysis.
- Long-Context Memory: The model can stay focused across millions of tokens during long-running tasks, utilizing persistent file-based memory to dramatically outperform earlier models like Opus 4.8.
Claude Mythos 5: Elite Power for Cyberdefenders and Scientists
While Fable 5 is available for general use, Anthropic is offering Claude Mythos 5 to a select group of cyberdefenders and infrastructure providers. Mythos 5 is the exact same underlying model as Fable 5, but with specific cybersecurity and biology safeguards lifted.
Initially deployed through Project Glasswing in collaboration with the US government, Mythos 5 boasts the strongest cybersecurity capabilities in the world. Its impact extends far beyond code, driving revolutionary breakthroughs in the life sciences:
- Accelerated Drug Design: Using Mythos 5 without human assistance, protein design experts accelerated aspects of the drug design process by around ten times, matching or beating skilled human operators.
- Novel Biological Hypotheses: Mythos 5 is Anthropic’s first model to consistently produce novel, compelling scientific hypotheses, including one mechanism for an E. coli protein that was independently corroborated by a real-world lab.
- Autonomous Genomics Research: Working largely autonomously for over a week, Mythos 5 successfully trained a custom machine learning model that outperformed a recent model published in the journal Science while being 100 times smaller.
Innovative Safety Architecture: The Opus 4.8 Fallback
Deploying Mythos-class capabilities comes with significant risks, particularly the potential for malicious actors to gain dangerous “uplift” in cybersecurity or bioweapon development. To ensure Fable 5 is safe for the public, Anthropic has implemented a revolutionary new safety classifier system.
Instead of outright refusing a potentially risky prompt, Fable 5’s classifiers intercept requests related to offensive cybersecurity, biology, chemistry, and AI distillation. When triggered, the system automatically routes the query to Claude Opus 4.8, ensuring users still receive a highly capable response rather than a frustrating rejection.
Currently, Anthropic has tuned these safeguards conservatively, meaning they trigger in less than 5% of sessions. For the other 95% of queries, Fable 5 delivers its full, unhindered Mythos-class performance. Anthropic has also introduced a new 30-day data retention policy for Mythos-class traffic to help defend against complex jailbreak attacks and refine these classifiers over time.
Pricing and Availability
Despite their massive leap in capability, Fable 5 and Mythos 5 are highly cost-effective. Both models are priced at $10 per million input tokens and $50 per million output tokens—less than half the cost of the previous Claude Mythos Preview.
Claude Fable 5 is available everywhere starting June 9, 2026, via the Claude API and Enterprise consumption plans. It is also included on Pro, Max, Team, and seat-based Enterprise plans at no extra cost through June 22, before transitioning to a usage credit system based on capacity. Developers can also access it on Amazon Bedrock and the Claude Platform on AWS.
Claude Mythos 5 is currently restricted to Project Glasswing partners, with plans to expand via a trusted access program for biomedical researchers and additional cybersecurity organizations in the near future.
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- Ollama Docker Sandbox: Run Local Models Safely — Run open-source AI models locally in a secure Docker sandbox as a Claude alternative.
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