RankingProgramBench · 166 golden-task subset

ProgramBench · 166 golden-task subset

Data updated 12 Sept 2026

Bucket
Supporting evidence
Unit
percent
Direction
Higher is better
Version
166 golden-task subset
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 5.1Anthropic87.6%
Reported settings & source

mini-swe-agent without six-hour timeout; excludes34flaky-reference tasks; tests restricted to reference-passing tests; up to1Mcontext.

Hidden-test pass rate, not fraction of completely solved programs. 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 · 8.11.1 · reviewed 2026-09-12

Claude Fable 5.1 and Claude Mythos 5.1 System Cardlab self-report2026-09-12
Claude Fable 5Anthropic86.3%
Reported settings & source

mini-swe-agent without six-hour timeout; excludes34flaky-reference tasks; tests restricted to reference-passing tests; up to1Mcontext.

Hidden-test pass rate, not fraction of completely solved programs. 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 · 8.11.1 · reviewed 2026-09-12

Claude Fable 5.1 and Claude Mythos 5.1 System Cardlab self-report2026-09-12
Claude Opus 5Anthropic85.4%
Reported settings & source

mini-swe-agent without six-hour timeout; excludes34flaky-reference tasks; tests restricted to reference-passing tests; up to1Mcontext.

Hidden-test pass rate, not fraction of completely solved programs.

Claude Fable 5.1 and Claude Mythos 5.1 System Card · 8.11.1 · reviewed 2026-09-12

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