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 human-avatar/skills-for-humanity --skill s4h-economics-margingit clone --depth 1 https://github.com/human-avatar/skills-for-humanityWrote 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/human-avatar/skills-for-humanity/s4h-economics-margin)<a href="https://agentmods.dev/skills/human-avatar/skills-for-humanity/s4h-economics-margin"><img src="https://agentmods.dev/badge/skills/human-avatar/skills-for-humanity/s4h-economics-margin/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/human-avatar/skills-for-humanity/s4h-economics-margin"><img src="https://agentmods.dev/badge/skills/human-avatar/skills-for-humanity/s4h-economics-margin.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 | $0.00109 | $0.01865 |
| Opus 5 | $0.00055 | $0.00932 |
| Sonnet 5 | $0.00022 | $0.00373 |
| Haiku 4.5 | $0.00011 | $0.00186 |
Grade A, and why
s4h-economics-margin 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 13d 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 — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Economics: Marginal Thinking
The most important word in economics is marginal. Not average. Not total. Not what we have spent. The relevant question is always: what happens at the next unit? Should we hire one more engineer? Produce one more batch? Add one more feature? Run one more campaign? The answer depends on the marginal cost (what that next unit costs) compared to the marginal benefit (what that next unit produces). When marginal benefit exceeds marginal cost, do more. When it doesn't, stop.
This sounds obvious. In practice, organisations almost universally fail to apply it. They use average cost when they should use marginal cost. They treat past expenditure as a reason to continue when it is economically irrelevant. They ask "should we have done this?" instead of "should we do more?" Alfred Marshall embedded marginal analysis at the heart of neoclassical economics precisely because pre-marginal thinking — evaluating the total or average rather than the increment — systematically produces wrong decisions.
The sunk cost fallacy is the most costly failure of marginal thinking. Resources already spent cannot be recovered — they are irreversible. They therefore cannot and should not influence forward decisions. Yet Kahneman's research confirms that people weight sunk costs heavily: the pain of a loss already incurred motivates continued investment in failing projects far more than forward-looking analysis would justify. This skill's core move is to strip sunk costs from the analysis and restate the decision in purely forward-looking marginal terms.
Your Process
Step 1: Identify the margin Clarify what the decision is actually about. Is it: (a) whether to do one more unit of something, (b) how many units to produce/do/hire, (c) whether to continue an existing project or commitment, (d) how to allocate resources across competing uses? The answer determines what "marginal" means in this context.
Framing check: Confirm the decision and the relevant margin before continuing. State what you've identified in one sentence, then use AskUserQuestion:
- Question: "I'm reading this as: [one-sentence framing — the decision and what unit is being considered at the margin]. Is that right?"
- Header: "Framing"
- Options:
- Yes — proceed — framing is correct
- Adjust — one element is off; user will correct it before you continue
- Reframe — different situation than read; incorporate the correction before proceeding
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.
- 13d ago First seen · 115 lines · 109 tokens per session scan A b02f8e8e132c
s4h-economics-margin is a skill published in the GitHub repository human-avatar/skills-for-humanity (223 stars, last pushed 1mo ago), licensed MIT. It adds 109 tokens to every session and 1,865 once invoked, about $0.0005 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 2026-08-30.
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