claude-fable-5 in the API at $10/M input and $50/M output tokens. Subscription users (Pro, Max, Team, Enterprise) get it included at no extra cost through June 22, after which usage credits are required.
What Happened
On June 9, 2026, Anthropic made its most capable model publicly available for the first time. Claude Fable 5 is a Mythos-class model with safeguards that redirect certain requests in cybersecurity, biology, chemistry, and model distillation to Claude Opus 4.8. According to Anthropic, these fallbacks occur in fewer than 5% of sessions, meaning most users interact with the full Mythos-class model.
Simultaneously, Anthropic launched Claude Mythos 5 — the same underlying model with some safeguards removed — exclusively for Project Glasswing partners: vetted cyberdefenders, critical infrastructure providers, and, eventually, life sciences researchers via a separate biology program.
- 🏆 Senior-Engineer Benchmark: Fable 5 → 91/100 vs Opus 4.8 → 63/100 vs GPT-5.5 → 62/100
- 💰 Pricing: $10/M input tokens · $50/M output tokens (2× Opus cost)
- 📅 Subscription free window: June 9 – June 22 (Pro, Max, Team, Enterprise)
- 🔗 Context window: 1 million tokens
- 🛡️ Safety fallback rate: <5% of sessions
Why Fable 5 Matters
A Step-Change in Coding Performance
Dan Shipper, CEO of Every, spent a week testing Fable 5 using an in-house "senior-engineer benchmark" — presenting the model with a real production codebase and asking how it would refactor it from first principles. Fable 5 scored 91 out of 100, matching a human senior engineer given a single prompt. The previous best was Opus 4.8 at 63. GPT-5.5 landed at 62.
The key differentiator isn't raw intelligence but autonomous endurance: Fable 5 takes on large, multi-file projects with fewer corrections and check-ins than previous models. It's designed for the kind of work where you hand off a project and come back to a result.
Updated Claude Model Tiers
| Tier | Use Case | Best For |
|---|---|---|
| Haiku | Ultra-fast, lightweight | Simple automation |
| Sonnet | Balanced | Everyday tasks |
| Opus | Complex collaboration | Synchronous complex work |
| Fable (Mythos-class) | Highest capability, public | Autonomous long projects |
| Mythos | Highest capability, restricted | Cybersecurity / infrastructure |
Install the SDK:
pip install anthropic. Then pass model="claude-fable-5" in your API call. For subscription users on Pro, Max, Team, or seat-based Enterprise, the model is included at no extra cost through June 22 — this is the window to run your most ambitious evaluations for free.Where Is It Available?
Fable 5 is live today across all major platforms:
- Claude API (model ID:
claude-fable-5) - Amazon Bedrock and Claude Platform on AWS
- Microsoft Foundry
- Claude.ai (Pro, Max, Team, and seat-based Enterprise through June 22)
On June 23, Anthropic will remove Fable 5 from subscription plans and require usage credits. The company says it intends to restore it as a standard subscription benefit as soon as capacity allows.
Project Glasswing is Anthropic's restricted access program for Mythos-class models, launched in April 2026 in collaboration with the US government. Glasswing partners — currently around 40 organizations including cloud providers, OS vendors, and critical infrastructure operators — receive access to Mythos 5, which has cybersecurity safeguards removed. A broader trusted-access program is in development to eventually expand Mythos access. A separate biology program will give selected life sciences researchers access with bio/chemistry safeguards removed while retaining cyber restrictions.
Industry Reactions
GitHub CEO Thomas Dohmke called Fable 5 "a real step forward for the developers GitHub serves," noting it tackled long-horizon coding tasks "with a level of autonomy and reliability that exceeded expectations." AWS launched Fable 5 on Amazon Bedrock the same day, describing it as built for "ambitious, long-running and complex work that previous models couldn't sustain."
- Claude Fable 5 is Anthropic's first publicly available Mythos-class model, launched June 9, 2026
- Scores 91/100 on the senior-engineer benchmark — 28 points above Opus 4.8 and GPT-5.5
- Available now via Claude API, Amazon Bedrock, Microsoft Foundry, and Claude.ai
- Subscription users get free access through June 22; usage credits required from June 23
- Mythos 5 (same model, safeguards removed) remains restricted to Project Glasswing partners