Model Routing

Deliberately matching each task to the cheapest model that is sufficient for it, instead of running everything on the frontier model. The practical-economics counterweight to ever-more-capable (and ever-more-expensive) models like Fable 5.

The argument (Matthew Berman)

The launch of Fable 5 at $10/$50 per million tokens (≈2× Opus) is the cleanest case for routing yet: you don't need Fable for the vast majority of use cases.

"You have the absolute frontier with Fable and you give it your most difficult problems… and then for everything else, you don't need it. You can go back to Sonnet. You can go back to Haiku."

• We're heading into a multi-model world; knowing which task goes to which model is a core skill.
• Enterprises are "already getting crazy bills" from Anthropic and OpenAI — routing is the cost-control lever.
• Effort levels are routing within a model: both creators advise starting at the lowest effort and dialing up only when needed (Fable on low ≈ Opus 4.8 on X-high, per Nate).
• Practitioner datapoint (I Turned Claude Fable Into The Ultimate Second Brain (Nate Herk)): Fable ate a $200/mo Max plan's 5-hour session limit in ~1 hour of stress-testing; Nate's mitigation is exactly routing — keep Fable for the lead session, delegate parallel sub-tasks to "cheaper workers" (Sonnet/Haiku) and collect one clean summary back.

Connects to the rest of the vault

• Token Maxing — routing is the demand-side mitigation for runaway token spend; pairs with the EFC "feedback-per-token" reframing. Don't pay frontier rates for work a mid-tier model nails.
• Build vs Buy (Agents) / enterprise cost discipline — Praveen's "decompose costs, tie to ROI" advice operationalizes the same instinct at org scale.
• Mythos-Class Models — the frontier tier that makes routing economically urgent (50× the output price of Haiku-class work).

Sources

• MYTHOS MYTHOS MYTHOS (Matthew Berman) (canonical for this framing)
• Claude Mythos is Finally Here (Nate Herk) (effort-level routing)