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 moeru-ai/auv --skill unsafe-checkergit clone --depth 1 https://github.com/moeru-ai/auvWrote 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/moeru-ai/auv/unsafe-checker)<a href="https://agentmods.dev/skills/moeru-ai/auv/unsafe-checker"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/unsafe-checker/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/moeru-ai/auv/unsafe-checker"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/unsafe-checker.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 | $0.00120 | $0.00674 |
| Opus 5 | $0.00060 | $0.00337 |
| Sonnet 5 | $0.00024 | $0.00135 |
| Haiku 4.5 | $0.00012 | $0.00067 |
Grade A, and why
unsafe-checker 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 10d 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
Display the following ASCII art exactly as shown. Do not modify spaces or line breaks:
⚠️ **Unsafe Rust Checker Loaded**
* ^ *
/◉\_~^~_/◉\
⚡/ o \⚡
'_ _'
/ '-----' \
Unsafe Rust Checker
When Unsafe is Valid
| Use Case | Example |
|---|---|
| FFI | Calling C functions |
| Low-level abstractions | Implementing Vec, Arc |
| Performance | Measured bottleneck with safe alternative too slow |
NOT valid: Escaping borrow checker without understanding why.
Required Documentation
// SAFETY: <why this is safe>
unsafe { ... }
/// # Safety
/// <caller requirements>
pub unsafe fn dangerous() { ... }
Quick Reference
| Operation | Safety Requirements |
|---|---|
*ptr deref |
Valid, aligned, initialized |
&*ptr |
+ No aliasing violations |
transmute |
Same size, valid bit pattern |
extern "C" |
Correct signature, ABI |
static mut |
Synchronization guaranteed |
impl Send/Sync |
Actually thread-safe |
Common Errors
| Error | Fix |
|---|---|
| Null pointer deref | Check for null before deref |
| Use after free | Ensure lifetime validity |
| Data race | Add proper synchronization |
| Alignment violation | Use #[repr(C)], check alignment |
| Invalid bit pattern | Use MaybeUninit |
| Missing SAFETY comment | Add // SAFETY: |
Deprecated → Better
| Deprecated | Use Instead |
|---|---|
mem::uninitialized() |
MaybeUninit<T> |
mem::zeroed() for refs |
MaybeUninit<T> |
| Raw pointer arithmetic | NonNull<T>, ptr::add |
CString::new().unwrap().as_ptr() |
Store CString first |
static mut |
AtomicT or Mutex |
| Manual extern | bindgen |
FFI Crates
| Direction | Crate |
|---|---|
| C → Rust | bindgen |
| Rust → C | cbindgen |
| Python | PyO3 |
| Node.js | napi-rs |
Claude knows unsafe Rust. Focus on SAFETY comments and soundness.
What ships with it
55 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.
- AGENTS.md 5.1 KB
- checklists/before-unsafe.md 3.3 KB
- checklists/common-pitfalls.md 4.5 KB
- checklists/review-unsafe.md 3.8 KB
- examples/ffi-patterns.md 8.8 KB
- examples/safe-abstraction.md 6.9 KB
- rules/_sections.md 1.9 KB
- rules/_template.md 765 B
- rules/ffi-01-no-string-direct.md 2.9 KB
- rules/ffi-02-read-ffi-docs.md 3.2 KB
- rules/ffi-03-drop-for-c-ptr.md 3.6 KB
- rules/ffi-04-panic-boundary.md 3.6 KB
- rules/ffi-05-portable-types.md 2.6 KB
- rules/ffi-06-string-abi.md 3.1 KB
- rules/ffi-07-no-drop-external.md 3.2 KB
- rules/ffi-08-error-handling.md 3.5 KB
- rules/ffi-09-ref-not-ptr.md 3.1 KB
- rules/ffi-10-thread-safety.md 3.2 KB
- rules/ffi-11-packed-ub.md 3.1 KB
- rules/ffi-12-invariant-doc.md 3.9 KB
- rules/ffi-13-data-layout.md 3.1 KB
- rules/ffi-14-stable-layout.md 3.0 KB
- rules/ffi-15-validate-external.md 3.6 KB
- rules/ffi-16-closure-to-c.md 3.5 KB
- rules/ffi-17-opaque-types.md 3.8 KB
- rules/ffi-18-no-trait-objects.md 3.8 KB
- rules/general-01-no-abuse.md 1.8 KB
- rules/general-02-not-for-perf.md 2.3 KB
- rules/general-03-no-alias.md 2.0 KB
- rules/io-01-raw-handle.md 3.7 KB
- rules/mem-01-repr-layout.md 2.9 KB
- rules/mem-02-no-other-process.md 3.1 KB
- rules/mem-03-no-auto-drop-foreign.md 3.2 KB
- rules/mem-04-reentrant.md 3.1 KB
- rules/mem-05-bitfield-crates.md 3.2 KB
- rules/mem-06-maybeuninit.md 3.8 KB
- rules/ptr-01-no-thread-share.md 2.9 KB
- rules/ptr-02-prefer-nonnull.md 2.7 KB
- rules/ptr-03-phantomdata.md 3.1 KB
- rules/ptr-04-alignment.md 3.1 KB
- rules/ptr-05-no-const-to-mut.md 2.8 KB
- rules/ptr-06-prefer-cast.md 3.0 KB
- rules/safety-01-panic-safety.md 2.9 KB
- rules/safety-02-verify-invariants.md 2.5 KB
- rules/safety-03-no-uninit-api.md 2.9 KB
- rules/safety-04-double-free.md 2.8 KB
- rules/safety-05-send-sync.md 2.9 KB
- rules/safety-06-no-raw-ptr-api.md 3.1 KB
- rules/safety-07-unsafe-pair.md 2.9 KB
- rules/safety-08-no-mut-from-immut.md 2.8 KB
- rules/safety-09-safety-comment.md 3.2 KB
- rules/safety-10-safety-doc.md 3.3 KB
- rules/safety-11-assert-not-debug.md 3.1 KB
- rules/union-01-avoid-except-ffi.md 2.6 KB
- rules/union-02-no-cross-lifetime.md 2.9 KB
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.
- 10d ago First seen · 87 lines · 120 tokens per session scan A 61dc44bbbe4d
unsafe-checker is a skill published in the GitHub repository moeru-ai/auv (27 stars, last pushed 2d ago), licensed Apache-2.0. It adds 120 tokens to every session and 674 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 2026-08-30.
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