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 jrgilbertson/the-rookery --skill creating-portable-skillsgit clone --depth 1 https://github.com/jrgilbertson/the-rookeryWrote 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/jrgilbertson/the-rookery/creating-portable-skills)<a href="https://agentmods.dev/skills/jrgilbertson/the-rookery/creating-portable-skills"><img src="https://agentmods.dev/badge/skills/jrgilbertson/the-rookery/creating-portable-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/jrgilbertson/the-rookery/creating-portable-skills"><img src="https://agentmods.dev/badge/skills/jrgilbertson/the-rookery/creating-portable-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 | $0.00041 | $0.00819 |
| Opus 5.5 | $0.00016 | $0.00328 |
| Sonnet 5.5 | $0.00008 | $0.00164 |
| Haiku 4.5 | $0.00004 | $0.00082 |
Grade A, and why
creating-portable-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 23d 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 — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Creating Portable Skills
Produce an installable package that does the user's reusable job and follows the Agent Skills specification, with useful evaluation cases and a grading method built through the upstream workflow.
For a read-only audit, apply references/review-checklist.md and return prioritized findings with file evidence and a verdict. For authorized creation, revision, or migration, use the workflow below. Existing authorization and the host project's constraints carry forward.
Author the package
Ground the skill in the user's intent, existing package, representative inputs and outputs, and corrections from real work. Identify the outcome and hard constraints that make completion acceptable. Check the host's contribution rules, discovery path, and existing owners before adding a workflow or helper.
For a new skill, use assets/skill-template.md. For a revision, the last commit can preserve the prior version. For a migration, revise a copy and preserve the source. Read references/portability.md when choosing frontmatter, bundling dependencies, or removing harness-specific assumptions.
Keep one instruction set for the job. Separate changing facts from reusable
instructions when that lets the next update change one source. Put conditional
guidance in references/, copied outputs in assets/, and deterministic helpers
in scripts/ when an existing mechanism cannot meet the requirement. Bundle
everything the package needs, or declare its actual environment dependencies.
Apply references/review-checklist.md while drafting. Preserve user authority, exact formats, privacy requirements, and fragile operation order; leave reasoning and implementation choices open.
Validate and evaluate
Use skills-ref validate <skill-directory> from an available trusted install.
If it is unavailable, check the specification's frontmatter rules, name-directory
match, body, and local resource links directly, and record the limitation. Exercise
bundled helpers with realistic inputs in disposable storage outside the host
project; preserve existing inputs and outputs.
What ships with it
5 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.
- 23d ago Changed · -16 lines · -32 tokens per session 6c84041f50ea
- 1mo ago Changed · -8 lines 42384ed836e1
- 1mo ago Changed · -6 lines ede24a3e5b54
- 1mo ago Changed · -2 lines 818aeb8497e7
- 1mo ago Changed · +2 lines · +18 tokens per session 407e3b8894e7
- 1mo ago Changed 8eac4b6902ee
- 1mo ago First seen · 109 lines · 55 tokens per session scan A 1146b6de5dc6
creating-portable-skills is a skill published in the GitHub repository jrgilbertson/the-rookery (12 stars, last pushed yesterday), licensed MIT. It adds 41 tokens to every session and 819 once invoked, about $0.0002 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 2026-08-31.
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