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 bostonaholic/team --skill principle-fail-closedgit clone --depth 1 https://github.com/bostonaholic/teamWrote 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/bostonaholic/team/principle-fail-closed)<a href="https://agentmods.dev/skills/bostonaholic/team/principle-fail-closed"><img src="https://agentmods.dev/badge/skills/bostonaholic/team/principle-fail-closed/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/bostonaholic/team/principle-fail-closed"><img src="https://agentmods.dev/badge/skills/bostonaholic/team/principle-fail-closed.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 | $0.00028 | $0.00167 |
| Opus 5 | $0.00014 | $0.00084 |
| Sonnet 5 | $0.00006 | $0.00033 |
| Haiku 4.5 | $0.00003 | $0.00017 |
Grade A, and why
principle-fail-closed 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 4d 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
Fail Closed
Reject any guarantee you cannot evaluate: Unknown counts as unsupported, a missing verdict counts as not passed, and inconclusive refutation keeps the finding.
- Never advance on a missing or unparseable verdict; retry once with the error, then halt loudly.
- Treat a failed capability check as unavailable and take the fallback path.
- Let refutation remove only confirmed false positives; never soften severity on an uncertain reply.
- Resolve ambiguous irreversible instructions safely, such as watching a draft instead of publishing it.
- Apply this rule to guarantees; degrade failed enhancements loudly under
principle-optimization-never-dependency.
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.
- 4d ago Changed · -14 lines · -14 tokens per session 4de4613b6b65
- 5d ago First seen · 30 lines · 42 tokens per session scan A 5d72c6f5d70e
principle-fail-closed is a skill published in the GitHub repository bostonaholic/team (11 stars, last pushed today), licensed MIT. It adds 28 tokens to every session and 167 once invoked, about $0.0001 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 2026-09-03.
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