# Claude Fable 5.1

Claude Fable 5.1 is an Anthropic language model released Sep 15, 2026; Anthropic's newest language model in our dataset is Claude Haiku 5.5. Proprietary, API access only. Anthropic's top-priced generally available Claude model, announced alongside the access-limited Claude Mythos on Sep 15, 2026. Verified against vendor sources on Oct 26, 2026.

Last verified: 2026-10-26 · Evidence: Reported · Canonical: https://theagenticweekly.com/models/claude-fable-5-1 · JSON: https://theagenticweekly.com/api/models/claude-fable-5-1

## Key facts

| Fact | Value | Source |
|---|---|---|
| Vendor | Anthropic |  |
| Released | Sep 15, 2026 | https://www.anthropic.com/news |
| API id | `claude-fable-5-1` | https://platform.claude.com/docs/en/about-claude/models/overview |
| Context window | 1,000,000 tokens (1M) | https://platform.claude.com/docs/en/about-claude/models/overview |
| Max output | 128,000 tokens | https://platform.claude.com/docs/en/about-claude/models/overview |
| Input | text, image | https://platform.claude.com/docs/en/about-claude/models/overview |
| Output | text | https://platform.claude.com/docs/en/about-claude/models/overview |
| Licence | Proprietary (API) | https://platform.claude.com/docs/en/about-claude/models/overview |
| Pricing | $10 in / $50 out per 1M tokens | https://platform.claude.com/docs/en/about-claude/models/overview |

## What we tested

Nothing yet. We have not run Claude Fable 5.1 ourselves, so every fact here is Reported from the sources below.

## Not verified, left out

- Claude Mythos 5.1 is listed by Anthropic with access limited to verification programs; we did not verify its specifications, so it has no entry.

## Sources

- [Anthropic models overview](https://platform.claude.com/docs/en/about-claude/models/overview)
- [Anthropic newsroom](https://www.anthropic.com/news)

Data licence: CC BY 4.0. Data: Agentic Weekly (https://theagenticweekly.com), CC BY 4.0.