🛠 Anthropic Cuts Claude Code System Prompt by 80%
The volume of instructions for Claude Code has decreased by more than 80% due to the transition to new Mythos-class models (Claude Opus 5 and Claude Fable 5), which handle tasks more effectively through internal logic and context engineering.
🌍 A shift is occurring from managing via massive instructions to utilizing the understanding built directly into the model's weights. This enables the creation of faster and cheaper AI agents with lower latency.
👤 Developers should note that old "safety net" methods involving massive instructions in CLAUDE.md may actually hinder the performance of these new models.
Source 1: https://claude.com/blog/the-new-rules-of-context-engineering-for-claude-5-generation-models Source 2: https://theagenttimes.com/articles/anthropic-cuts-80-of-claude-code-s-system-prompt-for-fable-5-b506c795