Claude Fable 5.2

// Overview

Claude Fable 5.2 is Anthropic's Mythos-class model released on 9 November 2026, built for the most demanding technical and open-ended work. It is the generally available half of the release: Claude Mythos 5.2 is the same underlying model with lighter cybersecurity and biology safeguards, offered only to vetted organizations through Anthropic's Cyber Verification Program and Life Sciences Verification Program. It reads text and images, has a 1M-token context window and up to 128K output tokens, with adaptive thinking always on (default effort high) and a June 2026 knowledge cutoff. The API model ID is claude-fable-5-2, and it is available on Amazon Web Services, Google Cloud and Microsoft Azure.

Standard pricing is $8 per million input tokens and $40 per million output tokens. An optional fast mode costs $16 and $80 per million tokens and speeds up token generation by up to 2.5 times. Anthropic says outputs are up to 30% faster than Fable 5.1 and Mythos 5.1. Fable 5.2 can also act as an Advisor or an Orchestrator for other Claude models.

Anthropic reports 69.9% on FrontierSWE v2 against 56.3% for Fable 5.1 and 62.3% for Claude Opus 5.5, and 41.3% on the Remote Labor Index against 17.9% for Fable 5.1. Its cyber and biology classifiers block about 55% fewer queries than Fable 5.1's. Anthropic recommends starting most coding and knowledge tasks on Claude Opus 5.5 and moving up to Fable or Mythos only when needed.

// Benchmarks

1. FrontierSWE v2 (agentic coding)69.9%
2. Remote Labor Index (knowledge work)41.3%
3. Humanity's Last Exam (with tools)74.2%
4. AutomationBench (business workflows)51.4%

Scores on a 0–100 scale (25-point gridlines); higher is better. Each benchmark links to its published source.

// Pricing

Optional fast mode $16/$80 per MTok, up to 2.5x faster generation. Claude Mythos 5.2 is available to verified organizations.

Pricing source ↗

// Strengths

• Agentic coding — 69.9% on FrontierSWE v2 and 49.1% on FrontierCode 2.0 at Xhigh effort
• Knowledge work — 41.3% on the Remote Labor Index and 51.4% on AutomationBench
• Standard price 20% below Fable 5.1's published $10/$50 per MTok
• Output up to 30% faster than Fable 5.1, with an optional fast mode up to 2.5x faster
• Cyber and biology classifiers block about 55% fewer queries than on Fable 5.1

// Best for

• Run long-horizon agentic coding where Claude Opus 5.5 still falls short on your own evals.
• Use Fable 5.2 as an Advisor or Orchestrator that steers cheaper Claude models in multi-agent setups.
• Automate business workflows and remote knowledge work end to end.

// How to access

// Claude Fable / Mythos (Mythos-class) — every version

The full lineage of the Claude Fable / Mythos (Mythos-class) line, newest first. Every version has its own page — click any to compare specs, benchmarks and pricing.