Fable Cost-Saving Trick: Strong Models for Judgment, Cheap Models for Execution
vista8 · x · 2026-07-07
Summarizing Simon Willison's cost-saving strategies for developing with Fable (also applicable to other models): 1) Add a rule in the Claude system prompt to let the model decide and select an appropriate low-power model for coding tasks running in a sub-agent; 2) Use Opus or Fable in the main loop for complex tasks like architecture design; 3) Let the loop autonomously call sub-agents for mechanical tasks like writing and modifying code, primarily using Sonnet and Haiku. The core idea is to separate judgment from execution: use strong models for judgment, and cheap models for execution.
Related event: Fable Uses Model Routing to Slash Token Costs(3 posts)→
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