RankingFrontierCode · 1.1 Main

FrontierCode · 1.1 Main

Data updated 24 Sept 2026

Bucket: Supporting evidence
Unit: percent
Direction: Higher is better
Version: 1.1 Main
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

Published configurations retain their source and harness labels. Missing results remain unknown.

1–4 of 4 entries

Model	Score	Harness	Evidence	Source-recorded date
Claude Fable 5Anthropic	53.5% Reported settings & source Cognition agentic coding; composite functional and code-quality score. Fable5.1 medium effort; Fable5 xhigh. 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 · 8.4 · reviewed 2026-09-24	Claude Fable 5.1 and Claude Mythos 5.1 System Card	lab self-report	2026-09-24
Claude Fable 5.1Anthropic	50.9% Reported settings & source Cognition agentic coding; composite functional and code-quality score. Fable5.1 medium effort; Fable5 xhigh. 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 · 8.4 · reviewed 2026-09-24	Claude Fable 5.1 and Claude Mythos 5.1 System Card	lab self-report	2026-09-24
Claude Opus 5.5Anthropic	54.4% Reported settings & source Cognition agentic coding in Claude Code; composite functional and code-quality score; max effort; mean@5. Cognition ran the evaluation. Provider-published lab self-report from the Claude Opus 5.5 system card (SHA256 7311c9c6bbb16d012f1c12c7418b05949fcf7ae3e30d2c40f22050074b2a7378). Not an independent board. Launch grid shows 54.4% for FrontierCode v1.1 (Main). Section 8.4 says performance falls above medium effort and this max-effort score is 54.4%. Comparison limit: Provider-published lab self-report. Shown as a labeled claim and not admitted as a matched board comparison. Claude Opus 5.5 System Card · Table 8.1.A; section 8.4 · reviewed 2026-09-22	Claude Opus 5.5 System Card	lab self-report	2026-09-22
Claude Opus 5.5Anthropic	54.6% Reported settings & source Cognition agentic coding in Claude Code; composite functional and code-quality score; medium effort; mean@5. Highest Main score. Cognition ran the evaluation. Provider-published lab self-report from the Claude Opus 5.5 system card (SHA256 7311c9c6bbb16d012f1c12c7418b05949fcf7ae3e30d2c40f22050074b2a7378). Not an independent board. Launch-page prose also states 54.6% at default (medium) effort. Comparison limit: Provider-published lab self-report. Shown as a labeled claim and not admitted as a matched board comparison. Claude Opus 5.5 System Card · section 8.4 · reviewed 2026-09-22	Claude Opus 5.5 System Card	lab self-report	2026-09-22