Anthropic cut 80% of Claude Code’s system prompt with no measurable loss
Roger_M_Taylor · x · 2026-07-26
The thread highlights a Claude Code article about “context engineering” for Claude 5 models, tying it to Herbert Simon’s idea of satisficing: real decision-makers do not optimize against every edge case, they choose something good enough for the real world.
Key points from the article:
- Anthropic removed about 80% of the Claude Code system prompt for its newest models.
- The change did not measurably hurt performance.
- The lesson is to write smaller, more focused system prompts and use skills / Claude.md to shape behavior instead of loading the prompt with every rule.
The post frames this as a practical redesign of agent instructions, not just a theory discussion.
Related event: Anthropic Slashes Claude Code System Prompts by Over 80%(11 posts)→
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