Traffic Controls

Smart Tier

Smart Tier chooses a model by request complexity rather than forcing one model for every call on a route.

How It Works Tiers Guardrails

How It Works

Complexity Routing

Input

Messages are scored 0–1 using the latest user turn and prompt structure.

→tier match

Routing Tiers

Simple, standard, and complex tiers map score ranges to models.

→selected model

Forwarded Request

Arc sends the request upstream with the chosen model.

Arc computes a conservative complexity heuristic in the proxy path. The latest user turn matters more than total prompt size so large context alone does not force aggressive upward routing.

Tier Configuration

json

[
  { "label": "simple",   "complexityMax": 0.35, "model": "gpt-4o-mini" },
  { "label": "standard", "complexityMax": 0.75, "model": "gpt-4o" },
  { "label": "complex",  "complexityMax": 1.00, "model": "gpt-4o" }
]

Arc selects the first tier whose complexityMax is greater than or equal to the score. The response model field reflects whichever model actually ran.

Guardrails

Conservative by design

Smart Tier should remain conservative about routing upward. The heuristic is useful routing input, not a ground-truth intelligence score.

Use shadow mode or canaries before changing important production routes. Smart Tier is strongest when cost is the main variable and the route already has stable prompt structure.

Rate Limiting

Shadow Mode And Canary