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.
npx skills add jared833/claude-code-hooks --skill build-toolgit clone --depth 1 https://github.com/jared833/claude-code-hooksWrote 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.
[](https://agentmods.dev/skills/jared833/claude-code-hooks/build-tool)<a href="https://agentmods.dev/skills/jared833/claude-code-hooks/build-tool"><img src="https://agentmods.dev/badge/skills/jared833/claude-code-hooks/build-tool/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.
<a href="https://agentmods.dev/skills/jared833/claude-code-hooks/build-tool"><img src="https://agentmods.dev/badge/skills/jared833/claude-code-hooks/build-tool.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00046 | $0.01171 |
| Opus 5.5 | $0.00018 | $0.00468 |
| Sonnet 5.5 | $0.00009 | $0.00234 |
| Haiku 4.5 | $0.00005 | $0.00117 |
Grade A, and why
build-tool 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 2mo 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.
How it starts
The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.
build-tool
Checklist for building one calculator tool. This one comes from a site of NEC electrical calculators, so the domain language is electrical, but the shape holds for any site whose tools have to be right rather than pretty.
Authoritative references live in the repo this runs against. Read them, do not duplicate them. The paths below are that repo's; substitute your own.
CLAUDE.mdfor accuracy principles, voice rules, the mandatory 7-part page template, exact disclaimer text, compliance flags.docs/voltage-drop-spec.mdfor the reference spec format.- Your own release playbook for everything after the build. This skill covers spec plus build
and stops there. See
pipeline/in this repo for the shape of one.
1. Spec first
Write docs/specs/<slug>-spec.md modeled on the reference spec: identity (name, slug,
target keyword, NEC edition + exact tables/articles), formula derivation with stated
assumptions, inputs (ranges/units/validation), output contract, 5 to 10 hand-derived
reference scenarios with arithmetic shown, documented deviations from third-party tools,
v1 out-of-scope list.
2. Four files
| File | Notes |
|---|---|
site/src/lib/calculators/<slug>.js |
Pure functions only. Comment header cites the NEC table/formula + edition + assumptions. |
site/src/lib/calculators/<slug>.test.js |
Vitest. The spec's 5 to 10 scenarios, arithmetic in comments, at least 1 cross-checked against a named independent tool. |
site/src/components/tools/<slug>-tool.astro |
Interactive UI, vanilla JS in <script>. No frameworks. Tool fully visible above the fold. |
site/src/pages/<slug>.astro |
7-part template; meta object (title with keyword + brand, about 60 chars; 120 to 155 char description; keyword; canonical optional, Layout derives the trailing-slash form); WebApplication + FAQPage JSON-LD. |
Color. Two roles, declared in site/src/styles/global.css and enforced by
npm run check:accent. Blue is action: the Calculate button, focus rings, the result hero,
in-content links. Amber is identity: the brand shell, cards, eyebrows, callouts. In a scoped
<style> block read the tokens (var(--action), var(--action-hover),
var(--action-text)) rather than writing a hex, and copy the block from an existing tool
instead of inventing one. Never put white text on amber, it is 2.15:1 and fails AA.
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.
- 2mo ago First seen · 89 lines · 46 tokens per session scan A 95b17a19fc32
build-tool is a skill published in the GitHub repository jared833/claude-code-hooks (2 stars, last pushed 4d ago), licensed MIT. It adds 46 tokens to every session and 1,171 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-31.
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