RankingFrontierSWE · 2

FrontierSWE · 2

Data updated 12 Sept 2026

Bucket
Supporting evidence
Unit
index
Direction
Higher is better
Version
2
Display harness
Claude Fable 5.1 and Claude Mythos 5.1 System Card
Board
https://www.anthropic.com/claude-fable-5-1-mythos-5-1-system-card

The available records have no admitted matched comparison in the capability core. Raw results remain available below.

Compare published benchmark results with category weights →

Models

ModelScoreHarnessEvidenceSource-recorded date
Claude Fable 5.1Anthropic0.57 fraction
Reported settings & source

Proximal agent harness; max effort; 34 tasks, five trials/task; mean score on 0..1 scale.

Fable is the safeguarded deployed configuration; selected tasks may use disclosed Opus fallback, except evaluations explicitly counting safety blocks as failures.

Claude Fable 5.1 and Claude Mythos 5.1 System Card · 8.5 · reviewed 2026-09-12

Claude Fable 5.1 and Claude Mythos 5.1 System Cardlab self-report2026-09-12
Claude Opus 5Anthropic0.52 fraction
Reported settings & source

Proximal agent harness; max effort; 34 tasks, five trials/task; mean score on 0..1 scale.

Claude Fable 5.1 and Claude Mythos 5.1 System Card · 8.5 · reviewed 2026-09-12

Claude Fable 5.1 and Claude Mythos 5.1 System Cardlab self-report2026-09-12
Claude Fable 5Anthropic0.48 fraction
Reported settings & source

Proximal agent harness; max effort; 34 tasks, five trials/task; mean score on 0..1 scale.

Fable is the safeguarded deployed configuration; selected tasks may use disclosed Opus fallback, except evaluations explicitly counting safety blocks as failures.

Claude Fable 5.1 and Claude Mythos 5.1 System Card · 8.5 · reviewed 2026-09-12

Claude Fable 5.1 and Claude Mythos 5.1 System Cardlab self-report2026-09-12
GPT-5.6 SolOpenAI0.32 fraction
Reported settings & source

Proximal agent harness; max effort; 34 tasks, five trials/task; mean score on 0..1 scale.

Claude Fable 5.1 and Claude Mythos 5.1 System Card · 8.5 · reviewed 2026-09-12

Claude Fable 5.1 and Claude Mythos 5.1 System Cardlab self-report2026-09-12