Stop Tuning Prompts. Build a Harness. (opens in new tab)

Anthropic shipped a piece earlier this month called . I have not read anything more useful about coding agents this year. The core claim, in their words: “the ecosystem built around the model—the harness—determines how Claude Code performs more than the model alone.” In my phrasing: in a real codebase, the model is the smaller variable. The layer of context and tooling you wire around the agent matters more than which version of Sonnet or Opus is behind it. The post stays high-level, which is...