Anthropic cuts down 80% of instructions to Claude code for Fable 5 models.

Modern AI models are “more creative than the examples we give them” and detailed examples and rules are considered constraints for these models.

That’s why Claude Code system prompt has been reduced by 80%, according to Anthropic’s technical team member Tariq Shihipar. Their new Fable 5 family of models “wants a smaller system prompt”.

It’s part of a paradigm shift in the way AI is being used. As models have evolved, the need for shorter prompts with many examples has given way to longer, more detailed ones. But now that things are going the other way again — the stronger the model, the less instructions it needs (as long as there’s a clear idea of what needs to be done and in what context).