RankingToolathlon · Verified June2026

Toolathlon · Verified June2026

Data updated 24 Sept 2026

Bucket: Supporting evidence
Unit: percent
Direction: Higher is better
Version: Verified June2026
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.

1–9 of 9 entries

Model	Score	Harness	Evidence	Source-recorded date
Claude Opus 5Anthropic	80.6% Reported settings & source Pass@1;108tasks/three trials; internal harness; max effort; Fable safeguards+Opus4.8fallback; Opus safeguards/fallback disabled; pinned containers/data. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table8.15.5.A · 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	77.8% Reported settings & source Pass@1;108tasks/three trials; internal harness; max effort; Fable safeguards+Opus4.8fallback; Opus safeguards/fallback disabled; pinned containers/data. 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 · Table8.15.5.A · 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	81.5% Reported settings & source Pass@3;108tasks/three trials; internal harness; max effort; Fable safeguards+Opus4.8fallback; Opus safeguards/fallback disabled; pinned containers/data. 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 · Table8.15.5.A · 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	73.1% Reported settings & source Pass³;108tasks/three trials; internal harness; max effort; Fable safeguards+Opus4.8fallback; Opus safeguards/fallback disabled; pinned containers/data. 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 · Table8.15.5.A · reviewed 2026-09-24	Claude Fable 5.1 and Claude Mythos 5.1 System Card	lab self-report	2026-09-24
Claude Opus 5Anthropic	87% Reported settings & source Pass@3;108tasks/three trials; internal harness; max effort; Fable safeguards+Opus4.8fallback; Opus safeguards/fallback disabled; pinned containers/data. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table8.15.5.A · reviewed 2026-09-24	Claude Fable 5.1 and Claude Mythos 5.1 System Card	lab self-report	2026-09-24
Claude Opus 5Anthropic	73.1% Reported settings & source Pass³;108tasks/three trials; internal harness; max effort; Fable safeguards+Opus4.8fallback; Opus safeguards/fallback disabled; pinned containers/data. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table8.15.5.A · 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	77.8% Reported settings & source Pass@1; 108 tasks; three trials; internal harness mirroring Toolathlon-Verified; adaptive thinking at max effort; safety classifiers on; one safety stop and six sandbox-monitor halts counted as failures. Provider-published lab self-report from the Claude Opus 5.5 system card (SHA256 7311c9c6bbb16d012f1c12c7418b05949fcf7ae3e30d2c40f22050074b2a7378). Not an independent board. 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 8.14.5.A · reviewed 2026-09-22	Claude Opus 5.5 System Card	lab self-report	2026-09-22
Claude Opus 5.5Anthropic	82.4% Reported settings & source Pass@3 (at least one of three trials correct); 108 tasks; internal harness; adaptive thinking at max effort; safety classifiers on. Provider-published lab self-report from the Claude Opus 5.5 system card (SHA256 7311c9c6bbb16d012f1c12c7418b05949fcf7ae3e30d2c40f22050074b2a7378). Not an independent board. 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 8.14.5.A · reviewed 2026-09-22	Claude Opus 5.5 System Card	lab self-report	2026-09-22
Claude Opus 5.5Anthropic	72.2% Reported settings & source Pass³ (all three trials correct); 108 tasks; internal harness; adaptive thinking at max effort; safety classifiers on. Provider-published lab self-report from the Claude Opus 5.5 system card (SHA256 7311c9c6bbb16d012f1c12c7418b05949fcf7ae3e30d2c40f22050074b2a7378). Not an independent board. 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 8.14.5.A · reviewed 2026-09-22	Claude Opus 5.5 System Card	lab self-report	2026-09-22