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 mathisk2095/jko-claude-plugins --skill rust-expertgit clone --depth 1 https://github.com/mathisk2095/jko-claude-pluginsWrote 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/mathisk2095/jko-claude-plugins/rust-expert)<a href="https://agentmods.dev/skills/mathisk2095/jko-claude-plugins/rust-expert"><img src="https://agentmods.dev/badge/skills/mathisk2095/jko-claude-plugins/rust-expert/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/mathisk2095/jko-claude-plugins/rust-expert"><img src="https://agentmods.dev/badge/skills/mathisk2095/jko-claude-plugins/rust-expert.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 | $0.00148 | $0.02258 |
| Opus 5.5 | $0.00059 | $0.00903 |
| Sonnet 5.5 | $0.00030 | $0.00452 |
| Haiku 4.5 | $0.00015 | $0.00226 |
Grade A, and why
rust-expert 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 1mo 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 — 162 lines — stays where its author put it; the contents beside it link to each section on GitHub.
This skill guides expert Rust development. Detect the project's edition and toolchain from Cargo.toml (edition, rust-version) and adapt guidance accordingly. Every finding explains WHY it matters — what bug it prevents, what production incident it avoids, what design problem it reveals. Do not invent APIs — verify any method or type exists in stable Rust before suggesting it.
How to Think About Rust Problems
Before fixing any issue, trace through the layers:
- Layer 3 — Domain (WHY): Business rules, performance constraints, deployment context. These constrain everything below.
- Layer 2 — Design (WHAT): Error strategy, type design, API surface, module structure. Check against SOLID and API Guidelines.
- Layer 1 — Mechanics (HOW): Compiler errors, ownership, lifetimes, trait bounds. Fix the immediate issue, but always trace UP.
When a compiler error appears, reframe it as a design question:
| Error | Don't Just Say | Ask Instead |
|---|---|---|
| E0382 (value moved) | "Clone it" | Who should own this data? |
| E0597 (doesn't live long enough) | "Add a lifetime" | Is the scope boundary correct? |
| E0277 (trait not satisfied) | "Add the bound" | Is this the right abstraction? |
| E0499 (two mutable borrows) | "Use RefCell" | Should this be two separate resources? |
| "future is not Send" | "Wrap in Arc" | Does this state need to cross threads? |
Ownership & Borrowing
→ Consult ownership reference for borrowing rules, Cow, smart pointers.
DO: Default to borrowing (&T). Move to owned only when the callee must store the value.
DO: Use &str and &[T] in function parameters — not &String or &Vec<T>.
DO: Use Cow<'_, str> when a function conditionally allocates.
DON'T: Clone to silence the borrow checker — restructure ownership instead.
DON'T: Over-annotate lifetimes — elision covers 95% of cases.
DON'T: Write &'a mut self on methods — borrows self for its entire lifetime.
Error Handling
→ Consult error-handling reference for thiserror/anyhow/snafu decision matrix.
What ships with it
16 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/ai-slop.md 12 KB
- references/anti-patterns.md 6.8 KB
- references/async.md 7.9 KB
- references/concurrency.md 12 KB
- references/design-principles.md 8.6 KB
- references/documentation.md 2.4 KB
- references/error-handling.md 3.8 KB
- references/macros.md 3.2 KB
- references/modules-cargo.md 5.4 KB
- references/ownership.md 4.8 KB
- references/performance.md 4.6 KB
- references/serde.md 3.3 KB
- references/testing.md 3.5 KB
- references/traits.md 4.3 KB
- references/type-patterns.md 5.6 KB
- references/unsafe.md 3.5 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.
- 1mo ago First seen · 162 lines · 148 tokens per session scan A 0c4b549df74c
rust-expert is a skill published in the GitHub repository mathisk2095/jko-claude-plugins (3 stars, last pushed 6d ago), licensed MIT. It adds 148 tokens to every session and 2,258 once invoked, about $0.0006 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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