Anthropic

Claude Fable 5

Released Jun 9, 2026 · knowledge cutoff 2026-01

Status: Frontier
Location: United States
Type: LLM
Modality: Multimodal
Context window: 1M
Max output: 128K
Speed (max effort): 74 tok/s · 107s to first answer token
Price ($/MTok in / out): $10 / $50
Cost per task (max effort): $2.75
Open weights: No

Benchmarks8 of 10 reported

GPQA Diamond

92.6%

SWE-bench Verified

95%

SWE-bench Pro

80.3%

Terminal-Bench 2.1

88%

Humanity's Last Exam

64.5%

LMArena Elo

1509

GDPval-AA v2

1723

ARC-AGI-2

89.2%

MMLU-Proretired

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AIME (latest)retired

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Strengths & weaknesses

Strengths

Holds decision quality steady across sessions that run for days, remembering why it chose something hours earlier
Plans in stages, delegates to sub-agents and checks its own work unprompted
Vision good enough to rebuild an interface from a screenshot
Acts rather than narrates — little time spent describing what it is about to do

Weaknesses

Keeps working until something stops it, so agent loops need explicit stop rules or the cost runs away
Slow, and its depth of explanation is a cost when you wanted a quick scan
Token spend and latency swing enormously between low and max effort, making budgeting hard

Shares weights with the restricted Claude Mythos 5 (vetted partners only). HLE 64.5% is with tools; GPQA/SWE figures are third-party — Anthropic retired saturated benchmarks from official reporting. Terminal-Bench 2.1 88.0% as reported in poolside's Laguna S 2.1 comparison table. ARC-AGI-2 89.2% is ARC Prize-verified at max effort ($5.45/task; xhigh 88.3%, high 87.5%), published 2026-06-09 at arcprize.org/results/anthropic-claude-fable-5. SWE-bench Pro 80.3% is Anthropic's own launch-table figure (2026-06-09, its own scaffolding; Mythos Preview 77.8, Opus 4.8 69.2, GPT-5.5 58.6, Gemini 3.1 Pro 54.2 in the same table, as reproduced by Vellum); trackers such as llm-stats and BenchLM round it to 80.0%.

For developers

API model strings

anthropicclaude-fable-5
aws-bedrockanthropic.claude-fable-5

Licence

Proprietary — weights not released

Retirement

No retirement announced

Lineage

No recorded predecessor

News