ai-dev-operating-system: Skill for Claude Code

.claude/skills/usage-monitor/SKILL.md

usage-monitor is a skill for Claude Code from lglucas/ai-dev-operating-system. It costs 68 tokens per session (803 once invoked), scanned A, original, MIT.

A post-launch report of real usage and spending across language-model providers, hosting, databases, and email services.

In plain words
What is it for?
It helps review bills after launches or metered features, track weekly usage, compare costs over time, and estimate the monthly spend.
Why use it?
It shows what the running product actually costs and highlights sudden increases or usage approaching free limits.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is lglucas/ai-dev-operating-system's own configuration. It tells Claude Code how to work on ai-dev-operating-system itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything ai-dev-operating-system configures →

Part of the ai-dev-operating-system plugin — 28 skills, 11 commands, 12 agents, 1 hook shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to lglucas/ai-dev-operating-system. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/lglucas/ai-dev-operating-system/main/.claude/skills/usage-monitor/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/lglucas/ai-dev-operating-system

Made for: Claude Code.

Or install ai-dev-operating-system, the plugin that ships this one along with the rest of its 28 skills, 11 commands, 12 agents, 1 hook.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for usage-monitor

README.md
[![agentmods](https://agentmods.dev/badge/skills/lglucas/ai-dev-operating-system/usage-monitor/github.svg)](https://agentmods.dev/skills/lglucas/ai-dev-operating-system/usage-monitor)
Your own site
<a href="https://agentmods.dev/skills/lglucas/ai-dev-operating-system/usage-monitor"><img src="https://agentmods.dev/badge/skills/lglucas/ai-dev-operating-system/usage-monitor/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for usage-monitor

Your own site · 80×15
<a href="https://agentmods.dev/skills/lglucas/ai-dev-operating-system/usage-monitor"><img src="https://agentmods.dev/badge/skills/lglucas/ai-dev-operating-system/usage-monitor.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 803 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00068 $0.00803
Opus 5 $0.00034 $0.00402
Sonnet 5 $0.00014 $0.00161
Haiku 4.5 $0.00007 $0.00080

Measured 12d ago against content hash c5f028dc96c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

usage-monitor scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/usage-monitor/SKILL.md · 81 lines

How it starts

The opening of the file, as written. The whole thing — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Usage Monitor

When to run this skill

  • 24h after a public launch.
  • Weekly during the first month after launch.
  • Whenever the user asks "quanto tá custando" / "tô gastando muito" / "como tá a fatura".
  • After a feature that calls a metered service ships.
  • When a billing alert fires.

Dashboard format

📊 Usage & cost — last 7 days

🤖 LLM (Anthropic):
   Input tokens:        1.2M (R$ 9.00)
   Output tokens:       340K (R$ 17.00)
   Cache reads:         800K (R$ 0.60)
   Total:               R$ 26.60
   Per active user:     R$ 0.27
   ⚠️  Up 340% vs prev week — investigate.

☁️  Hosting (Vercel):
   Bandwidth:           4.2 GB / 100 GB free
   Function invocations: 22K / 100K free
   Status:              🟢 within free tier

🗄️  Database (Supabase):
   DB size:             142 MB / 500 MB free
   Active users (mau):  18 / 50K free
   Status:              🟢 within free tier

✉️  Email (Resend):
   Sent:                240 / 3000 free
   Status:              🟢 within free tier

💰 Total billable this week: R$ 26.60
🔮 Projected month: R$ 114

Sources of truth

  • Anthropic: Console → Billing → Usage. API: /v1/organizations/usage_report.
  • Vercel: Dashboard → Usage tab.
  • Supabase: Dashboard → Project Settings → Usage.
  • Resend: Dashboard → Logs.
  • Stripe: Dashboard → Reports.

If the user hasn't connected a usage API: "para automatizar, preciso da chave read-only da [provider]. Sem ela, eu te lembro de checar manualmente toda segunda."

Triggers for action

Sinal Ação recomendada
LLM custo / usuário ativo > R$ 1 Revisar prompts, considerar Haiku, ativar cache.
Bandwidth > 70% do free tier Auditar imagens grandes, downloads.
DB > 70% do free tier Auditar tabelas grandes, archive.
Spike > 200% week-over-week Investigar imediatamente — provável loop / abuse.
Erro de cobrança / cartão recusado Avisar usuário no chat.

Vibe coder explanation

Imagina que cada serviço que você usa tem um relógio rodando. Toda semana eu olho os relógios pra você e falo: "tudo OK", "tá perto do limite", ou "tem algo estranho". Você não precisa entrar em 5 dashboards.

Read the full file on GitHub · 81 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 81 lines · 68 tokens per session scan A c5f028dc96c9

Subscribe to this mod's changes

usage-monitor is a skill published in the GitHub repository lglucas/ai-dev-operating-system (11 stars, last pushed 1mo ago), licensed MIT. It adds 68 tokens to every session and 803 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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