Borrowing it
Nothing to install: this file belongs to Aperivue/medsci-skills. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Aperivue/medsci-skills/main/CLAUDE.mdgit clone --depth 1 https://github.com/Aperivue/medsci-skillsWrote 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/instructions/aperivue/medsci-skills/claude-md)<a href="https://agentmods.dev/instructions/aperivue/medsci-skills/claude-md"><img src="https://agentmods.dev/badge/instructions/aperivue/medsci-skills/claude-md/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/instructions/aperivue/medsci-skills/claude-md"><img src="https://agentmods.dev/badge/instructions/aperivue/medsci-skills/claude-md.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 | $0.01314 | $0.01314 |
| Opus 5.5 | $0.00526 | $0.00526 |
| Sonnet 5.5 | $0.00263 | $0.00263 |
| Haiku 4.5 | $0.00131 | $0.00131 |
Grade A, and why
medsci-skills CLAUDE.md 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 8d 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 — 102 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Working in this repository
_corpus/heldout/ — do not read, do not run anything against it
This is the one instruction in this file that cannot be recovered from if you get it wrong.
_corpus/heldout/ holds a frozen set of real published papers whose entire purpose is to be
material no detector was written knowing about. Its protocol
(reverse_engineer/HELDOUT.md) states the spend rule directly:
| set | role | spent by |
|---|---|---|
| challenge-card fixtures | train | authored with the detector |
| the current corpus | validation | acting on a fire |
| a fresh frozen corpus | test — one unbiased number | reading it |
Reading is not a neutral act here. A fire rate measured on these papers asserts "no detector was written knowing this paper"; reading one in order to author or justify a change is exactly how a detector comes to know it. The protocol's own instruction is "Never open them again except to label a fire."
So, when working anywhere in this repository:
- Do not open
_corpus/heldout/*.md. - Do not run a detector, a grep, or a scan across
_corpus/. - Do not cite a number derived from it as evidence for changing a detector.
- If a task seems to require it, stop and ask. It almost certainly does not.
_corpus/ is gitignored, so git status will never show a change there and a clone will not carry
it. Neither fact protects it: anything scanning the working tree sees it. That is not
hypothetical — on 2026-07-31 an audit was launched against "the repository", three of its agents
reached _corpus/heldout/, and one ran a detector across the corpus and opened two of the papers.
The finding it produced was quarantined and not acted on, and the corpus in place was already spent,
so nothing measurable was lost. The next corpus is the one that reading destroys, and this file
exists because the fence was in a prompt instead of in the repository.
Merging your own pull requests
The maintainer has authorized Claude to merge a pull request it opened, without asking, when all of these hold: CI is green on the current head, there is no merge conflict, no review thread is open, and the change is one of:
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.
- 8d ago Changed · +8 lines · +152 tokens per session 6df6c901786c
- 23d ago Changed · +53 lines · +652 tokens per session cb3ed94f20ed
- 24d ago Changed · +2 tokens per session b1bf993fbfc2
- 1mo ago First seen · 41 lines · 508 tokens per session scan A 2684675c960a
medsci-skills CLAUDE.md is an instructions file published in the GitHub repository Aperivue/medsci-skills (349 stars, last pushed 2d ago), licensed MIT. It adds 1,314 tokens to every session, about $0.0053 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 2026-08-30.
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