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-Frontier-Labs-Inc/human-frontier-labs-marketplace --skill building-effective-skillsgit clone --depth 1 https://github.com/Human-Frontier-Labs-Inc/human-frontier-labs-marketplaceWrote 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-frontier-labs-inc/human-frontier-labs-marketplace/building-effective-skills)<a href="https://agentmods.dev/skills/human-frontier-labs-inc/human-frontier-labs-marketplace/building-effective-skills"><img src="https://agentmods.dev/badge/skills/human-frontier-labs-inc/human-frontier-labs-marketplace/building-effective-skills/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-frontier-labs-inc/human-frontier-labs-marketplace/building-effective-skills"><img src="https://agentmods.dev/badge/skills/human-frontier-labs-inc/human-frontier-labs-marketplace/building-effective-skills.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 | $0.00123 | $0.02391 |
| Opus 5 | $0.00062 | $0.01196 |
| Sonnet 5 | $0.00025 | $0.00478 |
| Haiku 4.5 | $0.00012 | $0.00239 |
Grade A, and why
building-effective-skills 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.
The source is not reproduced here
No licence file
A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.
What ships with it
9 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.
- references/authoring-anti-patterns.md 2.3 KB
- references/benchmark-protocol.md 5.2 KB
- references/distillation-checklist.md 2.0 KB
- scripts/gather.sh 1.5 KB runs code
- scripts/README.md 2.5 KB
- scripts/run-benchmark.js 6.2 KB runs code
- scripts/run-multiturn.js 5.1 KB runs code
- scripts/run-pairwise.js 5.7 KB runs code
- scripts/setup-domain.js 2.9 KB runs code
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 First seen · 98 lines · 123 tokens per session scan A ca7ce4702e17
building-effective-skills is a skill published in the GitHub repository Human-Frontier-Labs-Inc/human-frontier-labs-marketplace (6 stars, last pushed 1mo ago), with no licence file. It adds 123 tokens to every session and 2,391 once invoked, about $0.0006 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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