Claude Fable 5 is a Mythos-class flagship from Anthropic (United States).
One-line fit: best used for Hardest coding, board-level writing, careful agents.
Key specifications
| Provider | Anthropic |
|---|---|
| Model | Claude Fable 5 |
| Type | Mythos-class flagship |
| Context window | 1M in / 128K out (reported) |
| Pricing (indicative) | $10 / $50 per 1M |
| Company category | Frontier Lab |
| Region | United States |
| Official site | https://www.anthropic.com |
Benchmarks and public standing
SWE-bench Verified ~95%; SWE-bench Pro ~80.3%; often leads knowledge-work agent suites
Treat scores as directional. SWE-bench, Terminal-Bench, LMSYS Arena, Artificial Analysis, and vendor cards use different harnesses and are not always comparable 1:1. Re-check the latest official model card before decisions.
What this model is good at
Hardest coding, board-level writing, careful agents
This aligns with Anthropic’s broader strengths:
- Hard software engineering
- Long-form writing and research
- Computer use / Claude Code agents
- Enterprise trust and safety brand
Limitations and watch-outs
Expensive; capacity limits
- Rate limits, regional availability, and data retention policies vary by plan.
- Agent harness quality (Cursor, Claude Code, Codex, custom tools) can change outcomes more than raw model Elo.
- Open-weight availability (if any) is separate from hosted API quality and safety filters.
Ideal users
- Product engineers shipping features that match: Hardest coding, board-level writing, careful agents
- Teams standardizing on the Anthropic ecosystem
- Agent builders who need a Mythos-class flagship
When to pick something else
- Cheaper volume: compare lower tiers from the same lab or open Chinese/EU alternatives.
- Maximum hard SWE thoughtfulness: compare Claude Fable-class and other coding flagships.
- Giant multimodal corpora / Workspace: compare Gemini-class models.
- Self-host / open weights: Llama, Qwen, DeepSeek, GLM, Mistral open lines.
Parent company
Anthropic – Safety-focused frontier lab. Claude models are widely preferred for thoughtful coding, long writing, and high-stakes knowledge work.
Related models from Anthropic
- Claude Opus 4.x – Prior flagship tier
- Claude Sonnet 5 – Default Pro/Free workhorse
- Claude Haiku – Fast/cheap
- Claude Mythos (Glasswing) – Restricted cyber
Data is curated for AIForumSphere model directory mid-2026 directional figures.
