effort-router

Effort Router

Effort is the dial that trades intelligence for latency and cost on Fable 5. Two mistakes dominate: carrying over an old model's default effort unexamined, and picking one effort for an entire pipeline instead of per task class.

Defaults, not habits

• high is the API default and the right starting point for most analysis, writing, and agentic/coding work.
• medium (or low when latency is visible to a user) for routine transforms: classification, short edits, formatting.
• xhigh only for the tasks that actually need it: large migrations, one-way-door changes, multi-day autonomous runs.
• max almost never — reserve it for problems where xhigh measurably fell short, not as a default upgrade.

If you're migrating a harness built for Opus 4.7 or 4.8, don't keep xhigh "because that's what coding needs" — that guidance was for the older model. Re-test at high first; Fable 5 at high frequently matches or beats an older model at xhigh.

Route by task class

A triage step at low/medium that escalates only the cases that need it to high/xhigh beats any single fixed setting across a mixed workload — see job_packet/packet.py in this repo for a working example: prep and execute run cheap, plan_or_audit spends the premium effort only where judgment is dense.

Self-check

Before shipping a pipeline's effort settings, ask: if I doubled every effort level, would output quality visibly improve? If not, you're overpaying somewhere.