Introducing Claude Fable 5.1 and Claude Mythos 5.1

Benchmark Model Rank Results
agents-on-automationbench-private-v1-0-6Claude Fable 5.1 (max effort, with fallbacks) (Zapier AutomationBench)–Success Rate: 31.4
agents-on-terminal-bench-science-0-1Claude Fable 5.1 (max) (Claude Code)–Accuracy: 52.6
code-generation-on-deepsweClaude Fable 5.1 (max effort)–Pass@1: 0.674
code-generation-on-programbench-golden-166-no-time-limitClaude Fable 5.1 (max effort) (mini-swe-agent)–Average Test Pass Rate: 87.6
code-generation-on-swe-bench-multilingualClaude Fable 5.1 (max effort)–Accuracy: 89.1
code-generation-on-swe-bench-multimodalClaude Fable 5.1 (max effort)–Accuracy: 54.7
code-generation-on-swe-bench-proClaude Fable 5.1 (max effort)–Resolved: 81.2
code-generation-on-terminal-bench-4-0Claude Mythos 5.1 (max) (Claude Code --bare)–Accuracy: 60.9
medical-question-answering-on-healthbench-opus-4-8-grader-length-adjustedClaude Fable 5.1 (max effort, with fallbacks)–Score: 60.0
multi-task-language-understanding-on-global-mmluClaude Fable 5.1 (max effort)–Accuracy: 94.0
multi-task-language-understanding-on-miluClaude Fable 5.1 (max effort)–Accuracy: 93.0
question-answering-on-officeqa-pro-preselected-textClaude Fable 5.1 (max effort, with fallbacks)–Accuracy: 69.0