Anthropic's Advisor Tool and the Rise of "Inverted Agents"
Anthropic shipped something quietly significant this week: the Advisor Tool, a beta API feature that lets a cheap executor model (Sonnet or Haiku) consult a powerful advisor (Opus) mid-task without the developer orchestrating the handoff. On paper, it's a one-line API change — add a tool with type: "advisor_20260301" and a model: "claude-opus-4-6". But it represents a real architectural shift in how we think about inference economics, and it deserves more attention than the usual "new feature dropped" coverage.