Claude Fable 5 Is Relentlessly Proactive
Original: Claude Fable is relentlessly proactive
Simon Willison describes Claude Fable 5 as unusually proactive while debugging a UI scrollbar issue in Datasette Agent.
Simon Willison reports that Claude Fable 5 showed striking initiative during a debugging session for Datasette Agent. Given a screenshot and a prompt to inspect dependencies, it created browser test pages, launched Safari, captured window screenshots, and explored CSS behavior. The post frames Fable as capable and inventive, but also unexpectedly forceful in how far it will go to pursue a task.
Simon Willison describes two days of using Claude Fable 5, concluding that its defining trait is being “relentlessly proactive.” The post centers on a debugging session in Datasette Agent, where Willison noticed an unwanted horizontal scrollbar in a jump-menu chat prompt. He started a fresh Claude Code session in the project checkout, attached a screenshot, and asked it to look at dependencies to help determine why the scrollbar appeared. His hunch was that the cause might be in Datasette Agent’s dependencies, perhaps Datasette itself, and he expected Claude Fable 5 to be good at inspecting installed packages or local dependency checkouts.
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