# Anthropic — Claude Fable 5

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- This model's page: https://forck.live/models/claude-fable-5
- Anthropic's page: https://forck.live/company/anthropic
- Every model: https://forck.live/models
- Catalogue: https://forck.live/llms.txt

## Model

- Name: Claude Fable 5
- Company: Anthropic (anthropic.com)
- Launch post: not held by this record
- Announced: not stated
- Launch source: not stated
- Launch chosen by: not stated
- Released (per models.dev): 2026-06-07
- Listed (per OpenRouter): 2026-06-09
- Open weights: no
- Posts about it: 2
- Outlets named under its posts: 8
- Also written: Fable 5
- OpenRouter id: anthropic/claude-fable-5 — https://openrouter.ai/anthropic/claude-fable-5

## Posts about it

_Anthropic's own posts whose title names Claude Fable 5, and its launch post, in the record's order: dated newest first, undated last. The record reads the newest 50 first-party posts mentioning the model, every company's together, so a model mentioned more often than that lists the newest of them._

Every entry is one first-party announcement, and carries the same eight fields
in this order before any others:

    Company · Announced · Category · Coverage · Announcement · Group · Source · Record

`Source` is the company's own page the announcement was traced to and `Record`
is this site's page for it. Both are safe to cite.

`Coverage` is a number of outlets, or `not counted` — which means this record
reached no count of its own, never that nobody wrote about it.

`Category` is this tracker's own analysis, and is authoritative wherever it is
stated. `not stated` means either that nothing has analysed the post yet or
that the analysis placed it outside this taxonomy; neither is a verdict about
the announcement.

`Announcement` is whether the post is news of something the company did, rather
than a how-to, a customer story, a changelog listing or a staffing note.

`Group` is which of this record's groups the entry falls in, carried on the
entry itself so it holds where the groups are headings and where they are not.
One of: `models`, `covered`, `announcements`, `routine`.

Anything after `Record` is held detail that only some announcements carry.

### Anthropic — Working at the frontier: How Balyasny Asset Management evaluates and governs Claude Fable 5

- Company: Anthropic (anthropic.com)
- Announced: 2026-09-17
- Category: not stated
- Coverage: not counted
- Announcement: no
- Group: routine
- Source: https://claude.com/blog/working-at-the-frontier-how-balyasny-asset-management-evaluates-and-governs-claude-fable-5
- Record: https://forck.live/items/11768-working-at-the-frontier-how-balyasny-asset-management-evaluates-and-governs
- Subject: Claude

Balyasny Asset Management (BAM) uses Claude Fable 5 for complex financial tasks, evaluating it on thousands of real-world tasks where it achieved 89.4% accuracy versus 86.1% for the prior model. The firm built its own platform, BAMAgent, for deploying agents with governance controls, and treats safety as a product and operating-model question rather than a one-time model-selection exercise.

### Anthropic — Improving Fable 5's biology safeguards

- Company: Anthropic (anthropic.com)
- Announced: 2026-08-07
- Category: product-launch
- Coverage: not counted
- Announcement: yes
- Group: announcements
- Source: https://www.anthropic.com/news/improving-fable-5-s-biology-safeguards
- Record: https://forck.live/items/3653-improving-fable-5-s-biology-safeguards
- Subject: Claude

Anthropic announces updates to Claude Fable 5's biology safeguards that reduce false positives, cutting biology-related fallbacks by about 85%. This allows Fable 5 to assist with a wider range of biology tasks, including everyday health and educational questions, while still falling back to Opus 5 for dual-use requests.

## Who reported on it

_Outlets this record can name and link, under the first-party post each one covered. Their number is `Outlets named under its posts` above, and the rows are not totalled again. A post's own `Coverage` can be higher: it counts outlets the signal saw that this record cannot name and link._

### On: Improving Fable 5's biology safeguards

Record: https://forck.live/items/3653-improving-fable-5-s-biology-safeguards

- Blockchain News — Anthropic Enhances Biology Safeguards for Claude Fable 5: https://blockchain.news/news/anthropic-enhances-biology-safeguards-for-claude-fable-5
- Cyber Security News — Anthropic Updates Claude Fable 5's Biology Safeguards to Reduce False Positives: https://cybersecuritynews.com/claude-fable-5s-biology-safeguards-update
- Forkast — Anthropic Tightens and Loosens Fable 5 Biology Safeguards on the Same Day Stanford Proves AI Can Design Viruses: https://forkast.news/anthropic-tightens-and-loosens-fable-5-biology-safeguards-on-the-same-day-stanford-proves-ai-can-design-viruses
- Moneycontrol — Anthropic makes Fable 5 better at handling biology queries, cuts false positives by 85%: https://moneycontrol.com/technology/anthropic-makes-fable-5-better-at-handling-biology-queries-cuts-false-positives-by-85-article-13998502.html
- RuntimeWire — Anthropic cuts Fable 5 biology fallbacks while keeping research limits: https://runtimewire.com/article/anthropic-fable-5-biology-safeguards-fallbacks
- Tech Times — Claude Fable 5 Opens Biology for Clinicians: Researchers Wait on Broken Promise: https://techtimes.com/articles/323619/20260808/claude-fable-5-opens-biology-clinicians-researchers-wait-broken-promise.htm
- The Decoder — Anthropic loosens Fable 5's biology restrictions but keeps the guardrails on for virology and toxicology: https://the-decoder.com/anthropic-loosens-fable-5s-biology-restrictions-but-keeps-the-guardrails-on-for-virology-and-toxicology
- Unite — Anthropic Retunes Fable 5’s Biology Safeguards, Cutting Blocked Queries 85%: https://unite.ai/anthropic-retunes-fable-5s-biology-safeguards-cutting-blocked-queries-85

## Where it runs

_Other companies' own announcements naming Claude Fable 5 and Anthropic — each is that company's post, not Anthropic's._

### Amazon — Introducing Claude Fable 5.1 on AWS

- Company: Amazon (amazon.com)
- Announced: 2026-09-01T19:12:43+00:00
- Category: new-model
- Coverage: not counted
- Announcement: yes
- Group: models
- Source: https://aws.amazon.com/blogs/machine-learning/introducing-claude-fable-5-1-on-aws/
- Record: https://forck.live/items/7272-introducing-claude-fable-5-1-on-aws
- Subject: Bedrock / Nova

Amazon announces the availability of Claude Fable 5.1 on Amazon Bedrock, a new model with improved reasoning, agentic coding, autonomous operation, and scientific research capabilities. It is designated as a Covered Model with data retention policies and is available with Enterprise Frontier Safeguards for eligible customers.

### GitHub — Claude Fable 5.1 is generally available in GitHub Copilot

- Company: GitHub (github.com)
- Announced: 2026-09-01T14:29:23+00:00
- Category: availability-change
- Coverage: not counted
- Announcement: yes
- Group: announcements
- Source: https://github.blog/changelog/2026-09-01-claude-fable-5-1-generally-available-in-github-copilot
- Record: https://forck.live/items/7295-claude-fable-5-1-is-generally-available-in-github-copilot
- Subject: Copilot

Claude Fable 5.1 from Anthropic is now generally available in GitHub Copilot. It requires data retention by default for safety classifiers, with zero data retention available for eligible enterprise customers. The model is available to Copilot Pro+, Max, Business, and Enterprise users.

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