cost-watchdog

cost-watchdog is a skill for Claude Code, Codex from HugoRCD/evlog. It costs 55 tokens per session (1,372 once invoked), scanned A, original, MIT.

A weekly report on evlog's AI model spending and performance. It compares usage across application surfaces and models using current gateway data and pricing.

In plain words
What is it for?
Use it to review costs, token use, request counts, model selection, pricing, and performance by surface or model.
Why use it?
It shows whether each part of the system is still using a sensible model and whether spending or model choices have drifted.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to review costs, token use, request counts, model selection, pricing, and performance by surface or model.

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Install with agentmods
npx agentmods add skills/hugorcd/evlog/cost-watchdog
About the project

evlog is a TypeScript-first logging and observability project built around wide events and structured errors across runtimes. It is intended to help developers record application behavior and diagnose failures.

HugoRCD/evlog · 1,841 stars · on GitHub · evlog.dev

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add HugoRCD/evlog --skill cost-watchdog
Clone the repo
git clone --depth 1 https://github.com/HugoRCD/evlog

Made for: Claude Code, Codex.

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 cost-watchdog

README.md
[![agentmods](https://agentmods.dev/badge/skills/hugorcd/evlog/cost-watchdog.svg)](https://agentmods.dev/skills/hugorcd/evlog/cost-watchdog)
Your own site
<a href="https://agentmods.dev/skills/hugorcd/evlog/cost-watchdog"><img src="https://agentmods.dev/badge/skills/hugorcd/evlog/cost-watchdog.svg" alt="Measured on agentmods" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,372 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00055 $0.01372
Opus 5 $0.00028 $0.00686
Sonnet 5 $0.00011 $0.00274
Haiku 4.5 $0.00006 $0.00137

Measured 8d ago against content hash 4d9c46cd0ced, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

cost-watchdog 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 8d 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.

apps/evi/agent/skills/cost-watchdog/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cost and model watchdog

A recurring read of how evlog spends its model budget and whether the models in use are still the right ones. Run it weekly, on the last full week. Grounded in the AI Gateway report and the current model landscape, never in your memory of prices.

The core question: for every surface, is the model it runs still a sensible buy? The honest answer is often "yes, no change." A quiet week is a real result.

What the report gives you

ai_gateway__report with groupBy: 'tag' returns one row per tag value scoped to the current environment: the evi:env:* row (the total) plus one evi:surface:* row per surface. Each row carries total_cost, market_cost, input_tokens, output_tokens, cached_input_tokens, reasoning_tokens and request_count. groupBy: 'model' returns one row per model.

The surface list is whatever evi:surface:* rows the report actually returns. Do not assume the set; read it from the data.

Resources

Open these directly instead of searching; they are the stable home for everything the model-landscape step needs.

  • AI Gateway model catalog, as JSON (pricing and capabilities for every model in one fetch): https://ai-gateway.vercel.sh/v1/models
  • AI Gateway models browser (human-readable, filter by provider, pricing, latency, throughput): https://vercel.com/ai-gateway/models
  • AI Gateway docs, models & providers: https://vercel.com/docs/ai-gateway/models-and-providers
  • Model quality leaderboard (ex-LMArena, blind A/B human preference Elo): https://arena.ai/leaderboard
  • Independent cost-efficiency and benchmarks (Intelligence Index, Cost per Task, speed): https://artificialanalysis.ai/

Use web_search/web_fetch only for what these do not cover, such as a candidate model's fit for a specific surface. Every figure cited still needs a source and a recency.

Steps

1. Define the window

Run Monday morning. Cover the last 7 full days ending yesterday, and pull the 7 days before that as the comparison window, so every drift figure is period-over-period.

Read the full file on GitHub · 80 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. 8d ago First seen · 80 lines · 55 tokens per session scan A 4d9c46cd0ced

Subscribe to this mod's changes

cost-watchdog is a skill published in the GitHub repository HugoRCD/evlog (1,841 stars, last pushed yesterday), licensed MIT. It adds 55 tokens to every session and 1,372 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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