Tier Router

Tier Router

A two-tier routing pattern for Claude API calls. Default for 80% of calls is Haiku — fast, cheap, and sufficient for structured work. Escalate to Sonnet only when the task needs real reasoning.

When to use each tier

FAST (Haiku) — use by default:

• JSON extraction / structured output
• Summarization of a paragraph into a sentence
• Parameter generation with constraints
• Classification (sentiment, category, intent)
• Turning freeform text into a known schema
• "Which of these is X" single-choice selection

DEEP (Sonnet) — use only when:

• The task requires chains of reasoning over multiple facts
• The output quality is user-facing and visibly matters (final report, strategy critique)
• The decision has downstream cost if wrong (trade signal, architectural choice)
• The input requires synthesizing information the model must weigh and trade off

When in doubt, start with FAST and only escalate if the output is visibly worse.

Cost math

Typical Claude Code session: ~80% structured tasks + ~20% reasoning.

• All-Sonnet cost: 1.0 * $3.75 = $3.75 units
• Tiered cost: 0.8 * $1 + 0.2 * $3.75 = $1.55 units
• Savings: ~59% with no quality loss on the fast tier.

Real usage (orallexa trading agent) saw ~10x reduction because many calls are pure JSON parsing where Haiku is indistinguishable from Sonnet.

Install

pip install claude-tier-router

Usage

from anthropic import Anthropic
from tier_router import TierRouter

router = TierRouter(Anthropic())

# Structured -> Haiku
resp = router.fast(messages=[{"role": "user", "content": "Extract ticker as JSON: ..."}])

# Reasoning -> Sonnet
resp = router.deep(messages=[{"role": "user", "content": "Critique this strategy: ..."}])

# Inspect cost
print(router.cost_breakdown())
# {'fast_calls': 3, 'deep_calls': 1, 'fast_cost_usd': 0.002, ...}

Anti-patterns

• Don't use DEEP for JSON extraction — Haiku handles schemas reliably and costs 4x less.
• Don't use FAST for open-ended critique or strategy review — Haiku produces vague output.
• Don't hardcode model strings across your codebase. Import FAST_MODEL / DEEP_MODEL from tier_router so model upgrades land in one place.