Frugal

frugal

A cost-optimised agent router for Claude Code. Frugal teaches the main loop to send every sub-task to the cheapest execution strategy that can succeed, and to escalate only on verified failure:

The expensive reasoning model plans and judges; commodity work (locating files, extracting data, mechanical edits) runs on cheap tiers. No framework, no runtime, no API keys: frugal is a plugin made of a routing skill, five agent definitions, and two small hooks. The harness does the rest.

Install

How it works

The main model already reads every request, so it acts as the router at zero marginal cost. The routing skill gives it one decision table:

Plus a tool-first rule: if grep, jq, git, terraform or any deterministic command solves the task, no model is called at all.

Escalation (verification first)

Workers do not self-grade their way up the ladder. Every worker ends with a fixed footer:

The router then applies four rules:

1. If a deterministic check exists (tests, compiler, schema validation, terraform validate), run it. Pass = done. Fail = escalate one tier, maximum one retry, then the main loop takes over.
2. No check available: the main model spot-reads the result. It receives it anyway, so judging it costs almost nothing.
3. The worker's ESCALATE: yes is advisory input, never the sole trigger. Self-reported confidence from a cheap model is poorly calibrated; observable failure is not.
4. Never start at an expensive tier unless the decision table requires it. sage (Fable) is reached only via high-risk table rows or after escalation exhausts, one attempt, final.

Metrics and the cost report

A SubagentStop hook logs one jsonl line per worker run (agent, model, token usage, escalation flag) to ~/.claude/frugal/metrics.jsonl. Run:

to get cost per tier,…