m04-zero-cost

m04-zero-cost is a skill for Claude Code from actionbook/rust-skills. It costs 78 tokens per session (1,141 once invoked), scanned A, original, no licence file.

A guide to Rust generics and traits, which let code work with different types while sharing common behavior. It also covers static and dynamic dispatch and zero-cost abstractions.

In plain words
What is it for?
Use it for errors such as E0277, E0308, or E0599, and when working with generic types, trait bounds, impl Trait, dyn traits, or where clauses.
Why use it?
Generic and trait-based code can produce difficult compiler errors when type requirements do not match. This guide helps with those type relationships and implementation choices.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter.

Part of the rust-skills plugin — 38 skills, 21 commands, 4 agents, 1 hook, 1 MCP server shipped together

Good fit Use it for errors such as E0277, E0308, or E0599, and when working with generic types, trait bounds, impl Trait, dyn traits, or where clauses.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/actionbook/rust-skills/m04-zero-cost
Install

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.

Any agent
npx skills add actionbook/rust-skills --skill m04-zero-cost
Clone the repo
git clone --depth 1 https://github.com/actionbook/rust-skills

Made for: Claude Code.

Or install rust-skills, the plugin that ships this one along with the rest of its 38 skills, 21 commands, 4 agents, 1 hook, 1 MCP server.

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 m04-zero-cost

README.md
[![agentmods](https://agentmods.dev/badge/skills/actionbook/rust-skills/m04-zero-cost/github.svg)](https://agentmods.dev/skills/actionbook/rust-skills/m04-zero-cost)
Your own site
<a href="https://agentmods.dev/skills/actionbook/rust-skills/m04-zero-cost"><img src="https://agentmods.dev/badge/skills/actionbook/rust-skills/m04-zero-cost/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 m04-zero-cost

Your own site · 80×15
<a href="https://agentmods.dev/skills/actionbook/rust-skills/m04-zero-cost"><img src="https://agentmods.dev/badge/skills/actionbook/rust-skills/m04-zero-cost.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 78 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,141 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. Third-party audits
  • Socket pass 18 Mar 2026
  • Snyk pass 15 Feb 2026
How audits are shown
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 $0.00078 $0.01141
Opus 5 $0.00039 $0.00571
Sonnet 5 $0.00016 $0.00228
Haiku 4.5 $0.00008 $0.00114

Measured 9d ago against content hash 3a2eed8faf0a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

m04-zero-cost 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 9d 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.

skills/m04-zero-cost/SKILL.md · 166 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

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. 9d ago First seen · 166 lines · 78 tokens per session scan A 3a2eed8faf0a

Subscribe to this mod's changes

m04-zero-cost is a skill published in the GitHub repository actionbook/rust-skills (1,443 stars, last pushed 16d ago), with no licence file. It adds 78 tokens to every session and 1,141 once invoked, about $0.0004 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.