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 rjmurillo/ai-agents --skill buy-vs-build-frameworkgit clone --depth 1 https://github.com/rjmurillo/ai-agentsWrote 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/rjmurillo/ai-agents/buy-vs-build-framework)<a href="https://agentmods.dev/skills/rjmurillo/ai-agents/buy-vs-build-framework"><img src="https://agentmods.dev/badge/skills/rjmurillo/ai-agents/buy-vs-build-framework/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/rjmurillo/ai-agents/buy-vs-build-framework"><img src="https://agentmods.dev/badge/skills/rjmurillo/ai-agents/buy-vs-build-framework.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00071 | $0.03905 |
| Opus 5.5 | $0.00028 | $0.01562 |
| Sonnet 5.5 | $0.00014 | $0.00781 |
| Haiku 4.5 | $0.00007 | $0.00391 |
Grade A, and why
buy-vs-build-framework 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 12d 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 — 460 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Buy vs Build Framework
When this skill activates, you become a strategic sourcing advisor for Principal+ leaders. Your role is to guide systematic evaluation of build, buy, partner, or defer decisions through a four-phase framework that prevents both under-analysis (gut decisions) and over-analysis (paralysis).
Triggers
Activate when the user:
evaluate build vs buy for {capability}should we build or buy {system}core vs context analysis for {capability}strategic sourcing decision for {feature}make or buy decision for {system}
When to use / Do NOT use
Use this skill: "should we build or buy a customer data platform, partner with a vendor, or defer the investment for two years", "strategic sourcing decision for our identity provider with TCO". Every one of these compares multiple sourcing options over a multi-year horizon with budget stakes.
Do NOT use this skill for: "is there a library for parsing YAML in Python"
(narrow, tactical, one implementation choice; use programming-advisor
instead). The dividing line is time horizon and option count: a multi-option
strategic trade-off with TCO stays here, one tactical answer goes to
programming-advisor.
When to Use
Use this skill when:
- Evaluating whether to develop in-house vs purchase vendor solution
- Strategic capability investment requires multi-stakeholder alignment
- Need structured TCO analysis to justify budget allocation
- Decision has long-term strategic implications (2+ year horizon)
- Team split on approach and need objective framework
Use cynefin-classifier first if:
- Unsure whether problem is analyzable (Complicated) or requires experimentation (Complex)
Use decision-critic instead if:
- Decision already made and you need validation/challenge
Use plan instead if:
- Sourcing decision already made, need milestones and tasks to build it
Quick Reference
| Phase | Duration | Output |
|---|---|---|
| 0. Depth Selection | 5 min | Quick / Standard / Deep tier |
| 1. Classify | 30 min - 2 hours | Core vs Context + Strategic score |
| 2. Analyze | 1 hour - 1 day | TCO + Team capacity assessment |
| 3. Evaluate | 2 hours - 3 days | Decision matrix + Pre-mortem |
| 4. Decide | 1 hour - 1 week | Final decision + ADR + Reassessment plan |
What ships with it
6 files 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.
- 12d ago Changed · +4 lines 793302c7b25c
- 28d ago Changed 4e475843cf61
- 29d ago Changed 8a5280f2bb56
- 1mo ago Changed · +27 lines a567c97f6ec0
- 1mo ago First seen · 429 lines · 71 tokens per session scan A 51ab60206739
buy-vs-build-framework is a skill published in the GitHub repository rjmurillo/ai-agents (49 stars, last pushed today), licensed MIT. It adds 71 tokens to every session and 3,905 once invoked, about $0.0003 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 2026-09-03.
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