Anthropic just benchmarked "Fable 5 orchestrates, cheap models execute": 96% of the performance at 46% of the cost. You can run this pattern in Claude Code today

Yesterday's ClaudeDevs thread published first-party numbers for two multi-model patterns ( docs ):

- Fable 5 as orchestrator, Sonnet 5 as workers: 96% of all-Fable performance at 46% of the cost (BrowseComp: 86.8% vs 90.8% accuracy, $18.53 vs $40.56 per problem)

- Sonnet 5 as executor, consulting a Fable 5 advisor: ~92% at ~63% (SWE-bench Pro)

The orchestrator split won on both axes. Their post covers the API and Managed Agents side. If you're a Claude Code subscriber, the same split works natively today, and that's what I want to share.

The mechanism is three built-in features:

- Subagent model: frontmatter. A file in ~/.claude/agents/ with model: haiku or model: sonnet pins that role to a cheaper tier, regardless of your main-session model.

- Per-agent effort:. Anthropic's Fable guidance says low effort on current models often matches previous-gen xhigh, so recon and mechanical roles run at effort: low nearly free of quality cost.

- One CLAUDE.md policy telling the main session what to delegate. It only speaks in role names, so nothing breaks when models rotate.

One gotcha worth knowing even if you build nothing: since v2.1.198 the built-in Explore subagent inherits your main-session model, so if you run Fable or Opus as your daily driver, background searches bill at Opus tier. A user-level agent named Explore with model: haiku shadows it back down.

I packaged this as pilotfish (six roles: haiku scouts, sonnet mechanical executor, opus judgment executor, an adversarial fresh-context verifier, and a security role kept off Fable because its classifiers misfire on benign security work). One paste installs it, it shows the full plan before touching anything, and uninstall is three reversible steps: https://github.com/Nanako0129/pilotfish

Honest scope notes: the official numbers are API benchmarks, so on a subscription the savings track directionally, not identically. If you just want cheaper sessions with zero setup, the built-in /model opusplan covers most of it. And treat any paste-a-prompt installer like curl | sh: the README has a tag-pinned variant and lists exactly which files to read first.

Disclosure: researched and mostly built with Claude Code itself, then red-teamed and e2e-tested. A deeper writeup of the quota mechanics (fallback behavior at billing boundaries, the two-bucket weekly limit, effort tiering) is in my post on r/ClaudeCode if you want the details.