Claude Fable 5 — relentlessly proactive at problem-solving
Simon Willison spent two days with Claude Fable 5 and found it stands out for aggressive, multi-tool problem-solving. When he spotted a horizontal scrollbar glitch in a Datasette Agent UI, he fed Fable a screenshot with minimal context.
Fable unprompted inspected dependencies, traced the issue to installed package code, and surfaced the root cause—without being told how to debug. It deploys whatever tricks it knows to reach the goal, not just answering the narrow question asked.