Anthropic's New Prompting Guide for Fable 5 (3 Changes That Save You Money)
In this brief monologue, Nick Perry introduces Anthropic's new prompting guide for their flagship model, Fable 5, and highlights three practical tips to reduce costs and improve control. First, because difficult tasks tend to run longer by default, he recommends adding a prompt that tells the model not to over‑plan. Second, he stresses the importance of setting explicit boundaries so the model knows what it can and cannot do, preventing it from going "loco." Third—and the most critical—he advises giving the model very specific instructions for handing tasks to subagents, because Fable 5 readily creates larger agent teams, which can quickly consume thousands of dollars if not tightly directed. The overall message is a cautionary, cost‑focused guide to prompt engineering for Fable 5.
