Model Router

name: model-router description: Route work to the cheapest model tier that can reliably complete it. Use when: (1) choosing a model for a task, (2) deciding model level for sub-agents, (3) escalating after a failed attempt, (4) avoiding premium-model overuse on routine work.

category: principles user-invocable: true

Model Router

Choose model tier by task complexity. Keep routine work cheap. Escalate only when required.

Core Policy

• Classify each task first: ROUTINE, MODERATE, or COMPLEX.
• Start with the lowest tier that can succeed.
• Escalate one tier after a quality failure.
• Keep sub-agents on the cheapest viable tier by default.

Task Classification

ROUTINE

Use lowest-cost tier.

Signals:

• File reads/writes
• Status checks and health checks
• Deterministic formatting/transformations
• Bulk fetch/lookup tasks with clear success criteria

MODERATE

Use mid-tier.

Signals:

• Multi-step synthesis
• Standard code generation/refactoring
• Non-trivial summaries
• Typical implementation tasks with known patterns

COMPLEX

Use top-tier.

Signals:

• Ambiguous requirements
• Novel debugging/root-cause analysis
• Architecture tradeoffs
• Security-sensitive reasoning
• Repeated failure on lower tiers

Escalation And De-escalation

• Escalate when output quality is insufficient for the task goal.
• Escalate one tier at a time.
• De-escalate when work returns to deterministic or repetitive operations.
• Document escalation reason in one sentence before switching tiers.

Sub-Agent Rules

• Default sub-agents to the cheapest tier that matches task class.
• Reserve high-tier sub-agents for clearly complex reasoning only.
• If parent agent is high-tier, do not inherit that tier by default.

Anti-Patterns

• Premium tier for file I/O or status checks.
• Premium tier for repetitive extraction and formatting.
• Immediate jump from lowest tier to highest tier without justification.
• Leaving routine follow-up tasks on high tier after a complex step is complete.

Quick Decision Flow

1. Classify task complexity.
2. Pick the lowest viable tier.
3. Run and evaluate output quality.
4. Escalate one tier only if needed.
5. De-escalate for routine follow-up.