Anthropic cut 80% of Claude Code's system prompt with no performance drop

dr_cintas · x · 2026-08-31

Anthropic deleted over 80% of Claude Code's system prompt without a drop in performance. They identified six redundant patterns: absolute rules (let the model judge), copy-paste examples (trap reasoning), cramming everything upfront (load on demand), repeating instructions (new models remember), manual memory logging (tools handle it), and written descriptions (files/tests work better). The author turned this into a prompt to check and prune your own prompts.

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