cost-verification-auditor
Audit LLM token cost estimates against actual API usage. Activate on 'cost verification', 'token estimate accuracy', 'API cost audit', 'estimation variance'. NOT for pricing lookups, budget planning, or cost optimization strategies.
npx skills add majiayu000/claude-skill-registry --skill cost-verification-auditor --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Cost Verification Auditor Verify that token cost estimates are within ±20% of actual Claude API usage. ## When to Use ✅ **Use for**: - Validating token estimation systems after implementation - Pre-deployment cost accuracy checks - Debugging unexpected API bills - Periodic estimation drift detection ❌ **NOT for**: - Looking up model pricing (use pricing docs) - Budget planning or forecasting - Cost optimization strategies - Comparing models by price ## Core Audit Process ### Decision Tree ``` Has estimator? ──No──→ Build estimator first (see Calibration Guidelines) │ Yes ↓ Define 3+ test cases (simple/medium/complex) ↓ Estimate BEFORE execution (no peeking!) ↓ Execute against real API ↓ Calculate variance: (actual - estimated) / estimated ↓ Variance ≤ ±20%? ──Yes──→ PASS ✓ │ No ↓ Apply fixes from Anti-Patterns section ↓ Re-run verification ``` ### Variance Formula ```typescript const inputVariance = (actual.inputTokens - estimate.inputTokens) / estimate.inputTokens; const outputVariance = (actual.outputTokens - estimate.outputTokens) / estimate.outputTokens; const costVariance = (actual.totalCost - estimate.totalCost) / estimate.totalCost; // PASS if both input AND output within
- When to Use
- Core Audit Process
- Decision Tree
- Variance Formula
- Common Anti-Patterns
- Anti-Pattern: The 500-Token Overhead Myth
- Anti-Pattern: Per-Node Accuracy Obsession
- Anti-Pattern: Peeking Before Estimating
- Calibration Guidelines
- Input Token Estimation
- Output Token Estimation
- Model Behavior
- Quick Fixes
- Verification Checklist
What does the cost-verification-auditor skill do?
Audit LLM token cost estimates against actual API usage. Activate on 'cost verification', 'token estimate accuracy', 'API cost audit', 'estimation variance'. NOT for pricing lookups, budget planning, or cost optimization strategies.
How do I install it?
Run `npx skills add majiayu000/claude-skill-registry --skill cost-verification-auditor --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From majiayu000/claude-skill-registry, a repository with 534 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.