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Simon Willison 博客T2·Tools

Anthropic Prompt Tweak Quintuples Claude Code Refactoring Success

Original title: Quoting Prompting Claude Fable 5.2
62AI Score

Anthropic documentation reveals that simply telling Claude Fable 5.2 the codebase is its own raised its rate of merging duplicated code from under 10% to roughly 50% in small coding-task tests. The finding shows that ownership framing strongly steers whether the model conservatively extends existing structure or actively refactors it.

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Claude Fable 5.2 responds closely to what the prompt says about who owns the code it works on. In Anthropic’s testing on small coding tasks, when a prompt said nothing about ownership or presented the code base as someone else’s, the model tended to add to the existing structure, even when that repeated existing code. [...] If you want the model to improve the structure as it works, say that the code is its own:

This codebase is yours: what it's for and how it's built are your call, and you'll keep building on it. In Anthropic’s testing on small coding tasks, the model merged repeated code in about half of the tries with this sentence, and in under a tenth of the tries without it.

— Prompting Claude Fable 5.2, Anthropic documentation

Tags: prompt-engineering, anthropic, generative-ai, ai, llms, claude-mythos-fable