Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/stdin/buy-vs-buildnpx agentmods add skills/stdin/buy-vs-build/buy-vs-build-adrWrote 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-adr)<a href="https://agentmods.dev/skills/stdin/buy-vs-build/buy-vs-build-adr"><img src="https://agentmods.dev/badge/skills/stdin/buy-vs-build/buy-vs-build-adr/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-adr"><img src="https://agentmods.dev/badge/skills/stdin/buy-vs-build/buy-vs-build-adr.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 | $0.00058 | $0.00450 |
| Opus 5 | $0.00029 | $0.00225 |
| Sonnet 5 | $0.00012 | $0.00090 |
| Haiku 4.5 | $0.00006 | $0.00045 |
Grade A, and why
buy-vs-build-adr 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 ADR
Capture non-obvious buy-vs-build decisions as Architecture Decision Records so the reasoning — and the trigger to revisit it — survives the pull request.
When to record
Record an ADR when a decision is non-obvious or hard to reverse:
- Adding or removing a dependency.
- Choosing a commercial service over owning a capability.
- Building something in-house.
- Picking one technical option over a comparable one (for example, Server-Sent Events over WebSockets).
Skip it for obvious, trivial, easily reversible choices. An ADR is a few sentences, not an essay — it mirrors the one-line decision note the rule already produces, just durable and reviewable.
How to record
ADRs live in docs/decisions/, numbered sequentially as NNNN-title.md. Use the next free number. Either run the helper:
node scripts/record-decision.js \
--title "Use Server-Sent Events for the live feed" \
--rung native-platform \
--decision "Stream updates with SSE over HTTP." \
--rejected "WebSockets, because the feed is one-way and full-duplex is unused." \
--revisit "the feed needs bidirectional messaging."
…or, if no helper is available, create docs/decisions/NNNN-title.md by hand with this shape:
# NNNN. <title>
- Status: Accepted
- Date: <YYYY-MM-DD>
- Rung: <do-nothing|built-in|native-platform|installed-dependency|open-source|commercial|in-house>
## Context
<requirement and constraints>
## Decision
<the option chosen>
**Tradeoff:** <why it wins>
**Rejected:** <next-best option> because <constraint>
## Consequences
Revisit if <specific trigger>.
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 · 58 lines · 58 tokens per session scan A 4502dad3fce0
buy-vs-build-adr is a skill published in the GitHub repository stdin/buy-vs-build (3 stars, last pushed 2mo ago), licensed MIT. It adds 58 tokens to every session and 450 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 2026-08-31.
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