AI agent skill · by @mergisi

Cost Optimizer

Trigger when the user asks to audit Claude Code costs, reduce token spend, says "my Claude bill is too high", "optimize my CLAUDE.md", "why is this project burning tokens", or "/cost-optimizer". Scans a project for the common Claude Code cost leaks and returns a prioritized fix list.

Archived 2026-10-23 · Source updated 2026-05-25 · License: MIT. Check the original repository for the latest version.

SKILL.md instructions

# Cost Optimizer

Audit a project's Claude Code setup for the handful of well-known cost leaks and output a prioritized remediation list. This is a static inspection — no pricing API calls, no guesswork about past spend.

## When to use

- "My Claude Code bill doubled this month — what's going on?"
- "Audit this project for token waste"
- "Why is my session context always huge?"
- Post-mortem after a runaway agent run

## What to check

Run each check and record `PASS` / `WARN` / `FAIL` with a short note.

### 1. CLAUDE.md size

```bash
wc -l CLAUDE.md .claude/CLAUDE.md 2>/dev/null
```

- **PASS:** under 100 lines
- **WARN:** 100-300 lines
- **FAIL:** >300 lines — this is prepended to every message, so every line costs tokens forever.

Fix: move reference material (API keys, runbooks, verbose examples) into skill files or `docs/`, and leave CLAUDE.md as a thin pointer.

### 2. Memory file bloat

```bash
find ~/.claude/projects -name 'MEMORY.md' -exec wc -l {} \;
find .claude/memory -type f -exec wc -l {} \; 2>/dev/null
```

- **WARN** if any memory file is >500 lines.
- **FAIL** if >1500 lines — memory should be a curated index with links to detail files, not a dump.

Fix: extract old sections into `memory/<topic>.md` detail files and link from the index.

### 3. Unused or shadowed skills

```bash
ls ~/.claude/skills/ .claude/skills/ 2>/dev/null
```

- Cross-reference with the skill invocations in the last 30 days of shell history or session logs if available.
- Skills that have never been invoked but have huge `SKILL.md` bodies (>300 lines) are loaded into the skill index every turn — prune them.

### 4. Subagent fan-out patterns

Grep the project for Task/agent launch patterns:

```bash
grep -rn 'TaskCreate\|subagent\|parallel.*agent' --include='*.md' --include='*.js' --include='*.ts' .
```

- **WARN** if the repo spawns >5 parallel subagents per run without aggregation — each spins up its own context window.
- **FAIL** if subagents re-read the whole repo instead of receiving a scoped prompt.

Fix: pass a short brief + a handful of file paths to each subagent, not the entire CLAUDE.md context.

### 5. Prompt cache hygiene

Look for `.claude/settings.json` and check if the project sets an unusually short cache TTL, or if hooks invalidate the cache every message (e.g. a hook that echoes a timestamp into the system prompt).

- **FAIL** any hook that injects `date` / `uuidgen` / random content into every turn — it kills the cache, 10x cost.

### 6. Model selection

Grep for explicit model pins:

```bash
grep -rn 'opus\|sonnet\|haiku\|claude-3\|claude-4' .claude/ CLAUDE.md 2>/dev/null
```

- **WARN** if Opus is pinned for routine tasks that Sonnet could handle. Recommend the `/model-cost-compare` skill for a per-task estimate.

### 7. Session file size

```bash
du -sh ~/.claude/projects/*/sessions 2>/dev/null | sort -h | tail -5
```

Huge session dirs suggest you never `/compact` long-running threads. Suggest periodic compaction.

## Output format

Print a ranked list. Top of the list = biggest win per effort.

```
Cost Optimizer — <project>

Priority 1 (FAIL)
  [CLAUDE.md]      412 lines — prepended every turn. Extract sections into skills/.
  [cache hygiene]  .claude/settings.json hook injects `date +%s` on SessionStart. Remove it.

Priority 2 (WARN)
  [memory]         MEMORY.md is 820 lines. Index top, details linked.
  [model pinning]  Opus 4.6 pinned in 4 skill files — 2 could drop to Sonnet 4.6.

Priority 3 (nice-to-have)
  [skills]         3 skills (haiku-card, foo, bar) never invoked in last 30 days.

Estimated impact: roughly halving per-turn overhead — validate with a before/after /cost check.
```

Do not invent dollar savings. You can estimate relative impact ("~30% smaller context") but not absolute currency unless the user provides their current bill.

## Example invocations

- `/cost-optimizer`
- "Audit this project for Claude Code cost waste"
- "My CLAUDE.md feels too big — what should I cut?"
- "Why is my prompt cache missing every turn?"