A tested prompt tones down Fable 5.1's "claudese"; Anthropic ships official prompting guide

omarsar0 · x · 2026-09-03

Developer omarsar0 shares a prompt he tested that actually works to reduce Claude Fable 5.1's signature "claudese" writing style. The linked resource is Anthropic's new official guide, Prompting Claude Fable 5.1, covering behavioral differences and fixes for a dozen scenarios: choosing effort levels, batching independent tool calls in agent loops, keeping conversation history append-only, tuning writing density, formatting in chat, quoting retrieved sources, finishing the whole task without re-asking, preserving constraints in compaction summaries, and limiting changes/tests to what the task asked for.

Related event: Anthropic Releases Official Prompting Guide for Claude Fable 5.1(9 posts)→

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