- Claude Fable 5 is a Mythos-class model that has been made safe for general use and exceeds the capabilities of any previous widely available models.
- Fable 5 shows exceptional performance in software engineering, knowledge work, vision, scientific research, and many other areas.
- The release of such a capable model like Fable 5 comes with risks; therefore, it has been launched with safeguards that redirect certain queries to the next-most-capable model, Claude Opus 4.8.
- Claude Mythos 5 is being launched alongside Fable 5 for a specialized group of cyberdefenders and infrastructure providers.
- Mythos 5 will be deployed in collaboration with the US government as an upgrade to Claude Mythos Preview.
- Both models, Fable 5 and Mythos 5, are priced at $10 per million input tokens and $50 per million output tokens, which is less than half the price of Claude Mythos Preview.
- Early tests of Fable 5 indicated that it compressed months of engineering into days, including a codebase migration in a 50-million-line Ruby codebase that would have taken a team over two months.
- On the Finance Benchmark for senior-level reasoning, Fable 5 achieved the highest score, with substantial gains in document-based reasoning and problem solving.
- Mythos 5 is reported to have accelerated the drug design process by around ten times using internal protein design experts.
- Mythos 5 is unique as it consistently produces novel scientific hypotheses and has conducted genomics research mostly autonomously.
Claude Fable 5 and Claude Mythos 5 launch with powerful new capabilities, reshaping how engineering and scientific tasks are approached.1236
Fable 5 has demonstrated the ability to compress engineering tasks, achieving results that would normally span months in just a few days. In one instance, it completed a codebase-wide migration in a day, a task that traditionally required a team over two months to finish with a 50-million-line Ruby codebase.
Similarly, Claude Mythos 5 stands out for its unparalleled cybersecurity capabilities, ensuring it is the optimal model for digital defense tasks. Mythos 5 has also shown remarkable effectiveness in scientific research, accelerating drug design processes by ten times and outperforming other models in generating novel scientific hypotheses.121314
In fact, during blinded comparisons, scientists preferred hypotheses generated by Mythos models ~80% of the time. The models are competitively priced at $10 per million input tokens and $50 per million output tokens, significantly lower than their predecessors. This combination of efficiency gains and affordability marks a substantial leap in AI technology, presenting significant potential benefits across numerous sectors.8
For users, these launches indicate a shift towards AI that not only meets but exceeds existing benchmarks for capability and performance.
“Claude Fable 5 and Claude Mythos 5 have been introduced, showcasing extraordinary capabilities in engineering and scientific research. Alongside their advancements, safeguards will limit responses on certain topics to other models.”
