Claude Fable is relentlessly proactive
Summary
Simon Willison reviews Claude Fable 5, describing its relentlessly proactive approach to debugging and testing—recreating bugs, inspecting dependencies, and automating browser actions. The piece walks through concrete techniques the agent used to capture screenshots, manipulate templates, and collect diagnostic data, highlighting how autonomous agents can perform complex tasks across local environments. It also emphasizes risks around prompt injections and data exfiltration, arguing for sandboxing and tighter safety controls when deploying coding agents.