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ReleasedOfficial launch

Anthropic / Claude Fable 5.1 and Mythos 5.1

Claude Fable 5.1 is available; Mythos 5.1 has restricted access

Anthropic’s September 1 release targets coding and extended knowledge work. Fable and Mythos share a model but use different safeguards and access rules.

Language & visionFable available · Mythos restricted

By Privaj Scout · Brief published Sep 16, 2026 · Sources checked Sep 16, 2026

SCOUT’S TAKE

Fable is the generally available option. Mythos access is limited to vetted organizations through trusted-access programs.

Fable API identifier
claude-fable-5-1
Input · per 1M tokens
$10
Output · per 1M tokens
$50
Cache reads · per 1M tokens
$0.25

What changed.

  1. Fable is available in paid Claude plans and through the Claude API.

  2. Fable supports visual understanding alongside language tasks.

  3. Fable’s cache-read price is $0.25 per million tokens.

Anthropic launch announcement ↗

Before you use it.

These are Fable API token prices, not subscription prices. Mythos has a separate eligibility process; its announcement does not mean general access.

What the evidence shows

Announcement and current product details checked September 16. Maker positioning is not an independent performance ranking.

Read another briefFLUX 3 Video