Claude Fable 5.1

REASONING CEILING

Released Sept 1, 2026; Anthropic's capability ceiling for agentic coding and knowledge work, with 75% cheaper cache reads and 52.6% on Terminal-Bench-Science.

Context

1,000,000 tokens

Architecture

Frontier MoE (Adaptive Thinking)

Official API (1M)

$10 in / $50 out

License

Proprietary API / Cloud Foundry

Published benchmarks · lab-reported

Vendor-published figures, not independently reproduced. Sources in Verification below.

SWE-BENCH

78.4%

TERMINAL-BENCH

52.6%

GPQA DIAMOND

74.8%

Quickstart

curl -s https://modelregistry.tirup.in/api/cli?model=claude-fable-5-1

API DOCS

BACK TO LEDGER

Sources

Claude Fable 5.1 API reference · Anthropic

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