Project AURIONAI Use-Cases Research & Innovation
multimodal LLM

Claude Fable 5.1

Anthropic's model for demanding reasoning and long-horizon agentic work; adaptive thinking always on, default effort high. Available via API, GitHub Copilot (admin opt-in) and Kiro limited preview.

Anthropic
Levelmodel
Classmultimodal LLM
Parametersnot in the notes
Context1,000,000
Released1 Sep 2026
Opennessproprietary
Runs onnot in the notes
Statusactive

Benchmark Results

vendor-reportedindependent
Arena Text leaderboardhuman preference arena
maxindependent
1,501 ±6
1,2001,4001,600

Score in Elo; the axis starts at 1,200, as Elo has no zero. Higher is better.

rank 6, Arena Text overall8 Oct 2026 arena.ai
Arena Vision leaderboardhuman preference arena
maxindependent
1,286 ±10
1,2701,2901,310

Score in Elo; the axis starts at 1,270, as Elo has no zero. Higher is better.

rank 17 of 165, Arena Vision overall, style control default, 165 models9 Oct 2026 arena.ai
maxindependent
53
04590

Score in index. Higher is better.

rank 5 of 205, AA leaderboard, 205 current models10 Oct 2026 artificialanalysis.ai
vendor-reported
82
04590

Score in index. Higher is better.

benchlm.ai frontier top 69 Oct 2026 benchlm.ai
GDPval-AA v2.1agents and tool use
vendor-reported
1,735
1,6001,7501,900

Score in Elo; the axis starts at 1,600, as Elo has no zero. Higher is better.

Humanity's Last Exam (HLE)knowledge and reasoning
Table mixes runs with and without toolsvendor-reported
65
050100

Score in %. Higher is better.

rank 1, BenchLM aggregator, top score10 Oct 2026 benchlm.ai
IOIcoding
Vals.ai, max effortindependent
90.78 ±4.65
050100

Score in %. Higher is better.

Vals.ai, max effortindependent
90.52 ±0.86
050100

Score in %. Higher is better.

rank 1 of 143vals.ai
Vals-run variantindependent
90.5
050100

Score in %. Higher is better.

rank 1, Vals.ai run shown on BenchLM10 Oct 2026 benchlm.ai
MMMUmultimodal
Vals mirrorindependent
90.64
050100

Score in %. Higher is better.

Vals.ai mirror shown on BenchLM10 Oct 2026 benchlm.ai
OSWorld 2.0agents and tool use
vendor-reported
80.7
050100

Score in %. Higher is better.

Vals.ai, max effortindependent
7 ±1.81
050100

Score in %. Higher is better.

Terminal-Bench 2.1agents and tool use
Vals.ai, max effort; 79.03% if fallback-assisted tasks count as failuresindependent
85.02
050100

Score in %. Higher is better.

Terminal-Bench 4.0agents and tool use
Vals.ai, max effortindependent
58.08 ±3.31
050100

Score in %. Higher is better.

Where this comes from
Every score names who ran it: vendor-reported, maintainer-run or independent. A rank is shown with the population it was ranked in (gap rule 3).

Lineage

successorproduct of
Claude Fable 5 to Claude Fable 5.1: successor, medium confidenceClaude Mythos 5 to Claude Fable 5: product of, low confidenceClaude Mythos 5Claude Mythos 5AnthropicClaude Fable 5Claude Fable 5Anthropic, Jun 2026Claude Fable 5.1Claude Fable 5.1Anthropic, Sep 2026
AnthropicClaude Fable 5 is the parent (successor)medium confidencenotes
Where this comes from
Parent and child relations from model cards, Hugging Face base_model fields and the genealogy tables of the research notes. The tree shows two generations each way, 3 models. Confidence and evidence are the notes' own.

R&D Topics

Identity

Developer
Anthropic
Family
Claude
Released
1 Sep 2026 sourcessecondary reportunverified
Weights published
–
Record checked
10 Oct 2026
Where this comes from
Developer and dates from the research notes. Release date is the vendor's public announcement; weights date is when open weights were published.

Architecture and Size

Architecture
not in the notes Not disclosed
Total parameters
– sources
Active parameters
–
Checkpoint parameters
–
Context length
1,000,000 tokens
Input
text, image
Output
text
Where this comes from
Parameter counts as the developer states them. Where the checkpoint holds a different total, both are shown (register A16).

Openness and Access

Openness
proprietary
Licence
Proprietary sources
Access routes
API
Where this comes from
The licence file governs over registry tags and aggregator labels.

Deployment

Runs on
not in the notes
Footprint
Vendor cloud/API only (T1). Max output 128K tokens.
Runtimes
not in the notes
Where this comes from
Deployment tiers and runtimes as named in the notes. Footprint is the notes' figure, not a measurement by AURION.

Indonesia

Indonesian support
not stated
Regional languages
not in the notes
Jakarta hosting
unknown
Languages
Anthropic docs state all current models support multilingual capabilities; Bahasa Indonesia not verified
Where this comes from
Indonesia fields are carried on every model; unknown is an allowed value.

Industry Use Cases

No industry use case links this model.

Sources

  1. Models overview platform.claude.com/docs/en/models/overview https://platform.claude.com/docs/en/models/overview
  2. Best AI models, October 2026: Opus 5.5, GPT-6, Gemini slash-digital.io https://slash-digital.io/en/insights/ai-models-2026/
  3. LLM Leaderboard - Comparison of AI models from OpenAI, Anthropic, Google, SpaceXAI & others | Artificial Analysis artificialanalysis.ai https://artificialanalysis.ai/leaderboards/models
  4. Claude Fable 5.1 Benchmarks, Cost and Capabilities | Vals AI vals.ai https://vals.ai/models/anthropic_claude-fable-5-1
  5. Models overview platform.claude.com/docs/en/about-claude/models/overview https://platform.claude.com/docs/en/about-claude/models/overview
  6. Supported AI models in GitHub Copilot - GitHub Docs docs.github.com https://docs.github.com/en/copilot/reference/ai-models/supported-models
  7. Models - Docs - Kiro kiro.dev https://kiro.dev/docs/models/
  8. HLE Leaderboard: Claude Fable 5.1 Leads at 65% benchlm.ai https://www.benchlm.ai/benchmarks/hle
  9. Best LLM for Coding (October 2026): SWE-bench & LiveCodeBench Ranked benchlm.ai https://benchlm.ai/coding
  10. MMMU Leaderboard & Scores , October 2026 benchlm.ai https://www.benchlm.ai/benchmarks/mmmu

To cite this page: Project AURION, AI Use-Cases Research & Innovation, "Claude Fable 5.1", https://aurion.semai.id/models/anthropic-claude-fable-5-1/, records of October 2026.