---
format: "aidr-story-markdown/v1"
id: "57b112cceac5711b29224c34637ffa5b7a69099b4c7020b23c9dff9bda419a57"
canonical_url: "https://aidr.today/57b112cc?lang=en"
title: "Anthropic Launches Fable 5.1 and Mythos 5.1 With 75% Lower Cache Costs"
lang: "en"
requested_lang: "en"
available_langs: ["en","vi"]
translation_fallback: null
fallback_fields: []
published_at: "2026-09-01T18:51:47.000Z"
category: "Models"
topics: ["anthropic","fable","coding","inference","claude","arc-agi-2","agent"]
source_urls: ["https://huggingnews.com/ai/anthropic-launches-fable-51-and-mythos-51-with-75percent-lower-cache-cos-94edbaa9","https://x.com/claudeai/status/2094848572143407483","https://x.com/claudeai/status/2094848581425377479","https://x.com/claudeai/status/2094848588190830982","https://x.com/claudeai/status/2094848590245965931","https://x.com/claudeai/status/2094848579558953258","https://x.com/sarahzorah/status/2095128952402563542","https://x.com/btibor91/status/2095084209329385631"]
summary: "The new models optimize for complex, long-running tasks and scientific research. Fable 5.1 recorded a 52.6% score on Terminal-Bench-Science 0.1, more than double the performance of Fable 5, and 55.8% on Terminal-Bench 4.0 against 42.0% for its predecessor. These performance gains accompany a 75% reduction in cache read costs, which lowers the total price by 25% for typical usage and 45% for agentic workloads. Enterprise Frontier Safeguards (EFS) introduce zero data retention for corporate clients to maintain privacy while blocking adversarial use. This security feature begins a phased rollout this fall. Anthropic positions the Fable and Mythos 5.1 models as the world's most advanced available tools for coding and knowledge work."
---

# Anthropic Launches Fable 5\.1 and Mythos 5\.1 With 75% Lower Cache Costs

> [Open the canonical story](<https://aidr.today/57b112cc?lang=en>)

**Published:** 2026-09-01T18:51:47.000Z
**Category:** Models
**Topics:** anthropic, fable, coding, inference, claude, arc\-agi\-2, agent

## Summary

The new models optimize for complex, long\-running tasks and scientific research\. Fable 5\.1 recorded a 52\.6% score on Terminal\-Bench\-Science 0\.1, more than double the performance of Fable 5, and 55\.8% on Terminal\-Bench 4\.0 against 42\.0% for its predecessor\. These performance gains accompany a 75% reduction in cache read costs, which lowers the total price by 25% for typical usage and 45% for agentic workloads\. Enterprise Frontier Safeguards \(EFS\) introduce zero data retention for corporate clients to maintain privacy while blocking adversarial use\. This security feature begins a phased rollout this fall\. Anthropic positions the Fable and Mythos 5\.1 models as the world's most advanced available tools for coding and knowledge work\.

## Sources

- [Story source](<https://huggingnews.com/ai/anthropic-launches-fable-51-and-mythos-51-with-75percent-lower-cache-cos-94edbaa9>)
- [Story source](<https://x.com/claudeai/status/2094848572143407483>)
- [Supporting source](<https://x.com/claudeai/status/2094848581425377479>)
- [Supporting source](<https://x.com/claudeai/status/2094848588190830982>)
- [Supporting source](<https://x.com/claudeai/status/2094848590245965931>)
- [Supporting source](<https://x.com/claudeai/status/2094848579558953258>)
- [Story source](<https://x.com/sarahzorah/status/2095128952402563542>)
- [Supporting source](<https://x.com/btibor91/status/2095084209329385631>)