# Claude Fable 5

Anthropic, released 2026-06-09

**Verdict: conditional.** Anthropic's Mythos-class frontier model, the strongest publicly available Claude at its June 2026 launch, now listed as legacy behind Claude Fable 5.1. The verdict stays conditional on two constraints: API pricing of $10/$50 per 1M tokens, and a safety classifier that over-triggered on routine coding tasks at launch, routing them to an Opus 4.8 fallback. Subscribers reach Fable through Claude Max at 50% of weekly limits, or through usage credits on Pro. Anthropic's current lineup lists Fable 5.1 and Opus 5.5 for new work. Last verified 2026-09-30.

## Pricing

- Input: $10 / 1M tokens
- Output: $50 / 1M tokens
- Context: 1M ctx, 128K out; legacy; Max plans at 50% limits

## Strengths

- Long-horizon autonomous coding — compresses months of engineering into days (Stripe: 50M-line migration in 1 day vs 2-month team effort)
- Complex analytical reasoning — Hebbia Finance Benchmark #1, senior-research-scientist-grade hypothesis generation
- Vision-intensive tasks — state-of-the-art chart/table interpretation, rebuilds web apps from screenshots, beats Pokémon FireRed vision-only
- Agentic workflows with persistent memory — autonomously executes multi-turn tasks with file-based memory, self-corrects from notes
- Cybersecurity and biology queries — safety classifiers fall back to Opus 4.8; legitimate security/life-sciences work hits the safeguard wall
- Cost-sensitive high-volume production — at $50/1M output, batch processing costs compound aggressively vs GPT-5.5 at $30 or Opus 4.8 at $25
- Regulated environments with data-residency constraints — 30-day mandatory data retention for Mythos-class models is a compliance burden

## Benchmarks

- SWE-bench Verified: 95.0% (https://anthropic.com/claude-fable-5-mythos-5-system-card)
- SWE-bench Pro: 80.3% (https://anthropic.com/claude-fable-5-mythos-5-system-card)
- FrontierCode Diamond: 29.3% (https://anthropic.com/claude-fable-5-mythos-5-system-card)
- Terminal-Bench 2.1: 88.0% (https://anthropic.com/claude-fable-5-mythos-5-system-card)
- Humanity's Last Exam (tools): 64.5% (https://anthropic.com/claude-fable-5-mythos-5-system-card)
- GDPval-AA: 1932 Elo (https://anthropic.com/claude-fable-5-mythos-5-system-card)
- LiveCodeBench: 89.78% (https://anthropic.com/claude-fable-5-mythos-5-system-card)

## Sources

- [Anthropic Claude pricing page](https://claude.com/pricing)
- [Weights & Biases: Fable 5 Benchmark Scores](https://wandb.ai/byyoung3/ml-news/reports/Claude-Fable-5-Benchmark-Scores--VmlldzoxNzE3NTE3MQ)
- [Anthropic pricing page](https://platform.claude.com/docs/en/about-claude/pricing)
- [Anthropic Claude Fable 5 and Mythos 5 announcement](https://www.anthropic.com/news/claude-fable-5-mythos-5)
- [OpenRouter: Claude Fable 5 API Pricing & Benchmarks](https://openrouter.ai/anthropic/claude-fable-5)
- [Anthropic: System card](https://anthropic.com/claude-fable-5-mythos-5-system-card)
- [Anthropic: Claude Fable product page](https://www.anthropic.com/claude/fable)
- [LLM Stats: Claude Fable 5 Review, Benchmarks and Pricing](https://llm-stats.com/blog/research/claude-fable-5-review)
- [Let's Data Science: Anthropic Restores Fable 5 After US Ban](https://letsdatascience.com/news/anthropic-restores-fable-5-after-us-ban-9d5e2250)
- [Anthropic — Statement on US government directive](https://www.anthropic.com/news/fable-mythos-access)
- [Claude API docs: Models overview (Sonnet 4.6 and Sonnet 5 listed as legacy, still available; Sonnet 5.5 current)](https://platform.claude.com/docs/en/about-claude/models/overview)

Canonical: https://neomanex.com/models/fable-5