Anthropic

Claude Fable 5.1

A previous-generation reference: the same handwritten-edit sample exposes differences more concretely than an overall score.

Where it stands in the leaderboard

53points

Intelligence Index

Rank 3 among included models

max with fallback

Each model uses its highest tested setting on the source page, with fallback conditions retained; scores come from one evaluator.

Source read · 2026-10-02 · v4.3

Independent matched-task evaluation

2026-09-22Opus 5 → Opus 5.5
An update to complex work and communication, with public code-animation and same-prompt game examples.
Original release ↗
2026-09-28Sonnet 5 → Sonnet 5.5
The second 5.5-family model emphasizes everyday work, speed and effort-dependent costs.
Original release ↗