Anthropic Cut 80% of Claude Code's System Prompt with No Performance Drop
dr_cintas · x · 2026-08-31
Anthropic found that deleting over 80% of Claude Code's system prompt caused no drop in performance. The original text was mostly patches for old model habits rather than improvements. They identified six patterns of bloat: absolute rules (let the model judge), copy-paste examples (they limit reasoning), front-loaded detail (load on demand), repeated instructions (newer models remember), manual memory logging (tools save history), and written descriptions (show code/files instead). The author created a prompt to check your own files against these six patterns.
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