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-reviewgit 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-review)<a href="https://agentmods.dev/skills/stdin/buy-vs-build/buy-vs-build-review"><img src="https://agentmods.dev/badge/skills/stdin/buy-vs-build/buy-vs-build-review/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-review"><img src="https://agentmods.dev/badge/skills/stdin/buy-vs-build/buy-vs-build-review.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 | $0.00047 | $0.00490 |
| Opus 5 | $0.00023 | $0.00245 |
| Sonnet 5 | $0.00009 | $0.00098 |
| Haiku 4.5 | $0.00005 | $0.00049 |
Grade A, and why
buy-vs-build-review 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.
How it starts
The opening of the file, as written. The whole thing — 36 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Buy vs Build Review
Review the diff for ownership choices, not just correctness. Prefer findings that reduce risk, code, dependencies, or vendor lock-in without weakening safety.
Workflow
- Inspect changed files and dependency manifests.
- Flag custom code that a built-in, native platform feature, already-installed dependency, mature open source package, or commercial service should replace.
- Flag new dependencies or services that duplicate built-ins, installed packages, or tiny clear code.
- Check that the choice was implemented well, not just chosen well. The right rung integrated badly is still a finding: a wrapper that re-does the work the dependency already does, an SSE/WebSocket/queue added without handling its real failure modes (reconnect, retry, backpressure, idempotency), or a "reuse" that grew more glue code than it removed. Confirm the change actually cut code, failure modes, and operating burden.
- Preserve safety boundaries: validation, security, privacy, accessibility, observability, and explicit requirements.
- Judge the decision note as the reviewable artifact. Where the diff makes a non-obvious or hard-to-reverse choice, the note (in the PR body or a
docs/decisions/ADR) should name the distinguishing requirement, the rejected option, and a revisit trigger. A missing or vague note is itself a finding — it is often the most valuable thing in the change, because it is what makes the tradeoff reviewable later. - Report findings first, ordered by severity, with file references when possible.
Output
Use this shape:
Findings
- [severity] file:line - Issue. Better option: <rung>. Tradeoff: <why>.
Integration
- [severity] file:line - Right option, but: <unused capability / unhandled failure mode / glue code that outweighs the reuse>.
Decision gaps
- Missing or vague decision note for <choice> — name the distinguishing requirement, rejected option, and revisit trigger.
If there are no issues, say so and list any residual dependency or ownership risks.
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 · 36 lines · 47 tokens per session scan A f0323ae78e4c
buy-vs-build-review is a skill published in the GitHub repository stdin/buy-vs-build (3 stars, last pushed 2mo ago), licensed MIT. It adds 47 tokens to every session and 490 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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