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Anthropic releases Claude Fable 5.1 with improved science benchmark scores

Anthropic has released Claude Fable 5.1, a new iteration of their language model that reportedly sets new standards in coding, knowledge work, and long-running problem-solving. The model shows significant improvements on the Terminal-Bench-Science 0.1 benchmark, achieving a 52.6% score. User testing with a specific prompt to generate an animated pelican SVG revealed that higher reasoning effort settings on Fable 5.1 can lead to substantially more detailed outputs, albeit at a significantly higher cost and processing time. AI

IMPACT Sets new SOTA on scientific benchmarks, potentially influencing future model development and evaluation.

RANK_REASON Frontier-lab model release with system card.

Read on Mastodon — fosstodon.org →

AI-generated summary · Google Gemini · from 4 sources. How we write summaries →

Anthropic releases Claude Fable 5.1 with improved science benchmark scores

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0 / 100
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Frontier Release
Frontier-lab model release with system card.
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4 independent sources
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model release, product
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High
Clearly on-topic for AI-industry coverage.
Story freshness
51 days old
Aged out of breaking-news scoring windows; ranking reflects the durable signal from the full source set.

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COVERAGE [4]

  1. Simon Willison TIER_1 Română(RO) ·

    Claude Fable 5.1 made me a really nice animated pelican

    <p>Today is <a href="https://www.anthropic.com/claude-fable-and-mythos-5-1">Claude Fable (and Mythos) 5.1 day</a>. Anthropic say that Fable 5.1 "sets a new standard for coding, knowledge work, and long-running problem-solving tasks". Their announcement spends a notable amount of …

  2. Mastodon — fosstodon.org TIER_1 English(EN) · [email protected] ·

    Claude Fable 5.1 made me a really nice animated pelican → https:// simonwillison.net/2026/Sep/1/c laude-fable-5-1/ Anthropic hat gestern Fable 5.1 veröffentlich

    Claude Fable 5.1 made me a really nice animated pelican → https:// simonwillison.net/2026/Sep/1/c laude-fable-5-1/ Anthropic hat gestern Fable 5.1 veröffentlicht, das abermals besser sein soll und definitiv teuer sein wird. @ simon , der, wie ich letztes Jahr schon schrieb, "das …

  3. Mastodon — mastodon.social TIER_1 English(EN) · [email protected] ·

    Claude Fable 5.1 made me a nice animated pelican https://simonwillison.net/2026/Sep/1/claude-fable-5-1/ # HackerNews # Tech # AI

    Claude Fable 5.1 made me a nice animated pelican https://simonwillison.net/2026/Sep/1/claude-fable-5-1/ # HackerNews # Tech # AI

  4. Mastodon — mastodon.social TIER_1 English(EN) · [email protected] ·

    Claude Fable 5.1 made me a really nice animated pelican https://simonwillison.net/2026/Sep/1/claude-fable-5-1/ # AI # Python # OpenSource

    Claude Fable 5.1 made me a really nice animated pelican https://simonwillison.net/2026/Sep/1/claude-fable-5-1/ # AI # Python # OpenSource