Best AI Agent Skills for Ruby and Rails Developers (2026)
Rails has strong conventions and agents break them quietly. These SKILL.md skills encode ActiveRecord patterns, RSpec style, and Rails review criteria.
Rails has strong conventions and agents break them quietly. These SKILL.md skills encode ActiveRecord patterns, RSpec style, and Rails review criteria.
Quick Answer: The best skills for Ruby and Rails developers cover RSpec and Minitest generation, ActiveRecord N+1 prevention and scope conventions, Rubocop and standardrb formatting, service object patterns, and Rails security review. All use the SKILL.md format and work across Claude Code, OpenClaw, Codex CLI, Cursor, and other compatible agents. Browse them at agensi.io/skills.
Why generic skills fall short for Rails
Rails is convention over configuration, which means the conventions carry more weight than in most frameworks. Code that ignores them still runs, it just stops being Rails.
An agent needs to know: RSpec or Minitest, and if RSpec, whether the project uses let and subject or explicit setup. Whether business logic lives in models, service objects, interactors, or concerns. Whether the project uses Rubocop with the default config, standardrb, or a heavily customised ruleset. Whether it's Rails 7 with Hotwire and Turbo, or an older app with a separate JavaScript frontend. Whether Sidekiq, Solid Queue, or Active Job with a different adapter handles background work.
Get the architecture wrong and you get a 400-line controller action that works and that nobody on the team will accept.
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Testing skills
RSpec and Minitest are both idiomatic Ruby and completely different to write.
RSpec uses describe, context, it, and expectation syntax: expect(result).to eq(expected). Minitest uses classes extending ActiveSupport::TestCase with test "does something" do blocks and assertions: assert_equal expected, result.
A Rails testing skill should detect the framework from the Gemfile, know whether the project uses FactoryBot or fixtures, and follow the existing structure — whether specs are organised by class or by feature, and whether request specs or controller specs are the convention.
It should also know what not to test. Testing ActiveRecord validations that Rails already guarantees produces a slow suite full of noise.
Browse testing and QA skills on Agensi.
ActiveRecord and query patterns
ActiveRecord makes N+1 queries extremely easy to write and invisible until production.
The rule worth encoding: any association accessed inside a loop needs includes, preload, or eager_load on the parent query. A skill that states this catches the single most common Rails performance bug.
Other patterns worth defining: scopes on the model rather than chained conditions scattered through controllers, find_each rather than all.each for large collections, pluck when you only need columns rather than instantiating objects, and whether counter_cache is used rather than counting associations.
Migration conventions matter too — whether migrations are reversible, whether they're ever edited after deployment, and whether adding an index concurrently is required on large tables.
Browse database engineering skills on Agensi.
Code review for Rails
code-reviewer (764 installs, free) is the most installed skill on Agensi and works across languages for bugs, security, and error handling.
Rails-specific criteria worth adding:
Strong parameters. Every controller action taking user input needs explicit permitted params, never params.permit!.
Mass assignment and authorisation. Whether the project uses Pundit or CanCanCan, and that every action checks authorisation rather than relying on the view hiding a button.
Callback discipline. before_save chains that trigger other callbacks are where Rails apps become impossible to reason about. A skill can require that side effects live in service objects rather than model callbacks.
SQL injection. Any where("name = '#{params[:name]}'") is a finding. Parameterised conditions only.
Architecture and service objects
Where logic lives is the most consequential Rails decision and the one agents most often get wrong, because "fat model, skinny controller" and "service objects" are both well represented in training data.
A skill should state the project's answer plainly: whether service objects exist and what they're called (Services::CreateOrder, CreateOrderService, or an interactor pattern), what belongs in a model versus a service, and whether concerns are used or avoided.
Formatting and static analysis
Rubocop with a custom .rubocop.yml and standardrb are both common and they disagree with each other. State which one runs, because an agent formatting to the wrong one produces a diff full of style churn.
git-commit-writer (232 installs, free) writes conventional commit messages from staged changes and is language-agnostic.
env-doctor (86 installs, free) diagnoses why a project won't start, which for Rails is often a Ruby version mismatch against .ruby-version or a missing native gem dependency.
Installing these skills
~/.claude/skills/
├── code-reviewer/
│ └── SKILL.md
├── git-commit-writer/
│ └── SKILL.md
Claude Code reads from ~/.claude/skills/, OpenClaw from ~/.openclaw/skills/, Codex CLI from ~/.codex/skills/. Skills load at session start, so restart after adding one.
Full walkthrough: How to Install Skills in Claude Code.
Browse Ruby-compatible skills for any AI coding agent on Agensi.