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Simon Willison

What Simon Willison thinks about Anthropic

@simon-willison · 29 positions · 0 changes of mind

Co-creator of Django and creator of Datasette; writes daily at simonwillison.net.

Everything they publish, on ppll ↗

Simon Willison did not write this page.

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5 dated positions, 2026, in their own words. Our reading of what Simon Willison has said — not written or endorsed by them.

  1. Our readingA language model asked to summarize its own system prompt risks that prompt's content biasing the summary it produces.

    Their wordsI don’t trust Claude to summarize its own system prompts when there’s a risk that material from its system prompt might impact its opinions.

    ↗Claude's new system prompt really doesn't want to reproduce song lyricssimonwillison.net

    Interesting
  2. 3 weeks earlier

  3. Our readingClaude Haiku hallucinates badly enough that its use inside Claude Code's WebFetch tool is a hallucination risk on every fetched URL.

    Their wordsClaude Haiku is my current least favorite model - it hallucinates wildly, and is out-performed now by other similarly priced models like GPT-5.6-Luna Even worse: it seems to still be used by the Claude Code WebFetch tool, which means hallucination risk any time you fetch a URL!

    ↗@simonw on Xx.com

    OpenAI

    Interesting
  4. 5 months earlier

  5. Our readingThe frontier labs optimise their models for code above everything else because coding is where the money is: developers will pay $200 a month once a model is good enough.

    Their wordsOpenAI and Anthropic have both realized that code is the most important thing to optimize the models for, cuz that's where the money is. Like coders will spend $200 a month on a plan if it's good enough, it turns out.

    ↗Simon Willison: Engineering practices that make coding agents work - The Pragmatic Summityoutube.com 13th of 18 in this recording

    OpenAI

    Interesting

  7. Our readingThe interesting question is not what the next model will be able to do, but what the models already released can do that nobody has worked out yet.

    Their wordsI think the most interesting question is what can the models we have do right now? And so the only thing I care about today is what can Claude Opus 4.6 do that we haven't figured out yet. And I think it will take us 6 months to even start exploring the boundaries of that.

    ↗Simon Willison: Engineering practices that make coding agents work - The Pragmatic Summityoutube.com 14th of 18 in this recording

    Interesting

  9. Our readingDemand for open-source component libraries is collapsing, because a model will write exactly the widget you want instead of one you have to customise.

    Their wordsWhy would I use a date picker library where I'd have to customize it when I could have Claude write me the exact date picker that I want.

    ↗Simon Willison: Engineering practices that make coding agents work - The Pragmatic Summityoutube.com 17th of 18 in this recording

    Interesting