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 stdin/buy-vs-build --skill buy-vs-build-auditgit clone --depth 1 https://github.com/stdin/buy-vs-buildWrote 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/stdin/buy-vs-build/buy-vs-build-audit)<a href="https://agentmods.dev/skills/stdin/buy-vs-build/buy-vs-build-audit"><img src="https://agentmods.dev/badge/skills/stdin/buy-vs-build/buy-vs-build-audit/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/stdin/buy-vs-build/buy-vs-build-audit"><img src="https://agentmods.dev/badge/skills/stdin/buy-vs-build/buy-vs-build-audit.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 | $0.00044 | $0.00303 |
| Opus 5 | $0.00022 | $0.00151 |
| Sonnet 5 | $0.00009 | $0.00061 |
| Haiku 4.5 | $0.00004 | $0.00030 |
Grade A, and why
buy-vs-build-audit 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 11d 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.
What it actually says
Buy vs Build Audit
Audit the repository for ownership choices that deserve a second look. This is broader than a diff review: scan dependencies, common utilities, integration code, and high-maintenance subsystems.
Workflow
- Inspect dependency manifests and major source directories.
- Find custom implementations in standardized domains: dates, parsing, auth, crypto, queues, retries, validation, file formats, email, payments, observability, and search.
- Find dependencies that duplicate built-ins, native platform features, installed packages, or small clear code.
- Separate "fix now" from "watch later"; churn without payoff is not an improvement.
- Preserve safety boundaries: validation, security, privacy, accessibility, observability, and explicit requirements.
Output
Group results by action:
- Replace with reuse: custom code that should move to a built-in, platform feature, library, or service.
- Keep in-house: code that is core, small, constrained, or safer to own.
- Remove dependency: dependency that does not earn its ownership cost.
- Needs decision note: unclear tradeoffs requiring maintainer input.
For each item, include the likely rung, owner impact, and migration risk.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 11d ago First seen · 28 lines · 44 tokens per session scan A 33590f07bfc7
buy-vs-build-audit is a skill published in the GitHub repository stdin/buy-vs-build (3 stars, last pushed 2mo ago), licensed MIT. It adds 44 tokens to every session and 303 once invoked, about $0.0002 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 2026-08-31.
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