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rails-expert

rails-expert is a skill for Claude Code, Codex from johnefemer/skillfish. It costs 0 tokens per session (850 once invoked), scanned A, original, no licence file.

A Ruby on Rails engineering guide covering Rails data models, application structure, background jobs, testing, performance, and production changes.

In plain words
What is it for?
Use it when building or maintaining Rails features, defining service boundaries, working with background jobs, writing tests, or tuning performance.
Why use it?
It helps developers make safer changes in Rails applications while keeping the code organised and responsive.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

not rated 4repo 4d ago A scan 0 tokens no licence

Good fit Use it when building or maintaining Rails features, defining service boundaries, working with background jobs, writing tests, or tuning performance.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/johnefemer/skillfish/rails-expert
View source ↗ johnefemer/skillfish coach.omazy.ai
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 johnefemer/skillfish --skill rails-expert
Clone the repo
git clone --depth 1 https://github.com/johnefemer/skillfish

Made for: Claude Code, Codex.

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 rails-expert

README.md
[![agentmods](https://agentmods.dev/badge/skills/johnefemer/skillfish/rails-expert/github.svg)](https://agentmods.dev/skills/johnefemer/skillfish/rails-expert)
Your own site
<a href="https://agentmods.dev/skills/johnefemer/skillfish/rails-expert"><img src="https://agentmods.dev/badge/skills/johnefemer/skillfish/rails-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.

agentmods 80×15 button for rails-expert

Your own site · 80×15
<a href="https://agentmods.dev/skills/johnefemer/skillfish/rails-expert"><img src="https://agentmods.dev/badge/skills/johnefemer/skillfish/rails-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 850 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 $0.00000 $0.00850
Opus 5.5 $0.00000 $0.00340
Sonnet 5.5 $0.00000 $0.00170
Haiku 4.5 $0.00000 $0.00085

Measured 2mo ago against content hash c47f3f1820d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rails-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 2mo 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/rails-expert/SKILL.md · 77 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. 2mo ago First seen · 77 lines · 0 tokens per session scan A c47f3f1820d8

Subscribe to this mod's changes

rails-expert is a skill published in the GitHub repository johnefemer/skillfish (4 stars, last pushed 4d ago), with no licence file. It costs nothing until one of its globs matches a file; then it loads 850 tokens. 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 2026-09-03.

Backend and APIsLanguagesRuby
Related

rails-expert compared with skills from other repositories

rails-expert next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
rails-expertjohnefemer/skillfishSkill44d agononeA0Claude Code, Codex
rails-expertJeffallan/claude-skillsSkill12k7d agoMITA104Claude Code
newclacky-ai/openclackySkill1.2kyesterdayMITA10Claude Code
rails-conventionsrootstrap/rails_api_baseSkill6342d agoMITA71Claude Code
rails-idiomsirahardianto/awesome-agvSkill15823d agoMITA57Claude Code, Codex
rails-devtech-leads-club/agent-skillsSkill7.1kyesterdaynoneA199Claude Code, Codex
ruby-railsj4flmao/agent-skillsSkill383d agoMITA94Claude Code, Codex