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mutsu: Skill for Claude Code

.claude/skills/rustc-too-old/SKILL.md

rustc-too-old is a skill for Claude Code from tokuhirom/mutsu. It costs 161 tokens per session (1,568 once invoked), scanned A, original, Artistic-2.0.

A troubleshooting guide for Rust projects that fail because the installed rustc compiler or toolchain is older than the code requires.

In plain words
What is it for?
Use it to diagnose messages about unstable features, nightly Rust, language editions, or unsupported Rust syntax in a container build.
Why use it?
It focuses on compiler-version and language-feature errors instead of treating them as defects in the application code.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is tokuhirom/mutsu's own configuration. It tells Claude Code how to work on mutsu itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mutsu configures →

not rated 30repo changed 1mo ago A scan 161 tokens Artistic-2.0
View source ↗ tokuhirom/mutsu tokuhirom.github.io
Reuse

Borrowing it

Nothing to install: this file belongs to tokuhirom/mutsu. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/tokuhirom/mutsu/main/.claude/skills/rustc-too-old/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/tokuhirom/mutsu

Made for: Claude Code.

Wrote 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.

agentmods badge for rustc-too-old

README.md
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Your own site
<a href="https://agentmods.dev/skills/tokuhirom/mutsu/rustc-too-old"><img src="https://agentmods.dev/badge/skills/tokuhirom/mutsu/rustc-too-old/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.

agentmods 80×15 button for rustc-too-old

Your own site · 80×15
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Per session 161 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,568 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00161 $0.01568
Opus 5.5 $0.00064 $0.00627
Sonnet 5.5 $0.00032 $0.00314
Haiku 4.5 $0.00016 $0.00157

Measured 1mo ago against content hash ae70b4d3a7dd, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rustc-too-old 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.

.claude/skills/rustc-too-old/SKILL.md · 134 lines

The source is not reproduced here

Licensed Artistic-2.0

The repository is licensed Artistic-2.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

Changes

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.

  1. 1mo ago Changed ae70b4d3a7dd
  2. 1mo ago Changed 374986c82b5c
  3. 2mo ago First seen · 134 lines · 161 tokens per session scan A 6cc90f5be82e

Subscribe to this mod's changes

rustc-too-old is a skill published in the GitHub repository tokuhirom/mutsu (30 stars, last pushed today), licensed Artistic-2.0. It adds 161 tokens to every session and 1,568 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 2026-09-06.

DebuggingLanguagesRust
Related

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rust-errorBerriAI/litellmSkill63kyesterdaynoneA72Claude Code, Codex
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clickhouse-rust-type-mismatchesdivinevideo/divine-mobileSkill264yesterdayMPL-2.0A280Claude Code, Codex