Anthropic says Claude Code cut 80% of its system prompt with no coding loss

petrusenko_max · x · 2026-07-26

Anthropic says it cut more than 80% of Claude Code’s system prompt for Claude Opus 5 and Fable 5 without hurting coding performance.

The implication is that the models can rely less on brittle prompt rules and more on:

That makes the product easier to maintain and suggests a shift away from heavy prompt scaffolding in agent workflows.

Related event: Anthropic Slashes Claude Code System Prompts by Over 80%(11 posts)→

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