Craft CMS 5 — Extending (Plugins & Modules) Agent Skill

Craft CMS 5 plugin and module development — extending Craft with PHP.

Context cost
202.1k tokensestimated from the bundle; more than a 200k window holds
Bundle
31 files · 808.2 kBtext throughout, nothing executable
Licence
MITthe author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Craft CMS 5 plugin and module development — extending Craft with PHP. Covers elements, element queries, services, models, records, controllers, migrations, queue jobs, console commands, field types, native fields, events, behaviors, Twig extensions, widgets, filesystems, permissions, project config, GraphQL, testing, and debugging.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

contentphp

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md26.9 kB · preview
--- name: craftcms when_to_use: "Triggers on: beforePrepare()/afterSave()/defineSources()/defineTableAttributes()/attributeHtml(), MemoizableArray, BaseNativeField, EVENT_REGISTER_*/DEFINE_*/BEFORE_*/AFTER_*, CraftVariable, custom element or field type (normalizeValue/serializeValue/inputHtml), webhook, API endpoint, queue/batch job, CP section, dashboard widget, utility page, element action/exporter/condition, registerUserPermissions, requirePermission vs requireAdmin, kebab-case permission handles, allowAdminChanges, canView/canSave/canDelete, defineRules, elevated session, project-config/apply, drafts/revisions, element edit sidebar (EVENT_DEFINE_SIDEBAR_HTML) + toolbar buttons, metaFieldsHtml, VueAdminTable, GeneralConfig, getIsMultiSite/refreshSites stale after creating a site, deleteSite phantom sites, element query stops filtering by siteId, naive UTC datetime columns and strtotime drift, element-query ['like'] tuple matches nothing, configWarning config-file overrides. Always use when writing, editing, or reviewing Craft plugin/module PHP — even when no API is named. Plugin-specific work: also load craft-plugins. Do NOT trigger for front-end Twig (craft-site) or content modeling (craft-content-modeling)." ---
7# Craft CMS 5 — Extending (Plugins & Modules)
8
9Reference for extending Craft CMS 5 through plugins and modules. Covers everything from elements and services to controllers, migrations, fields, and events.
10
11This skill is scoped to **extending** Craft — building plugins, modules, custom element types, field types, and backend integrations. For site/platform development (content modeling, sections, entry types, Twig templating, plugin selection), see the craft-site skill.
12
13## Companion Skills — Always Load Together
14
15When this skill triggers, also load:
16
17- **craft-php-guidelines** — PHPDoc standards, section headers, naming conventions, class organization, ECS/PHPStan, verification checklist. Required for any PHP code.
18- **ddev** — All commands run through DDEV. Required for running ECS, PHPStan, scaffolding, and tests.
19- **craft-garnish** — When working on CP JavaScript, asset bundles, or interactive CP components. Covers Garnish's class system, UI widgets (Modal, HUD, DisclosureMenu, Select), drag system, and the Craft.* JS class pattern.
20- **craft-pest** — When writing, running, fixing, or reviewing tests. Covers the markhuot/craft-pest-core harness, database isolation (its rollback is opt-in and its env overrides are cwd-bound — both cause silent writes to the dev database), factories, HTTP/queue/DB assertions, and CI test jobs.
21- **craft-cloud** — When the project is hosted on Craft Cloud (detect via craft-cloud.yaml at the repo root or craftcms/cloud in composer.json). Required for plugin Cloud-compatibility constraints — App::isEphemeral() guards, asset-bundle CDN publishing, 15-minute queue-job cap, csrfInput() function over raw token output, and the cloud/up deploy lifecycle events.
22
23## Documentation
24
25- Extend guide: https://craftcms.com/docs/5.x/extend/
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md3,580 words
Files31
LicenceMIT
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈400
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
201,650
on trigger
The instruction body and 30 supporting files, read only when the skill fires.
1×
a 200k window
It does not fit in the window: loaded whole, it would need more room than the model has.
050k100k150k200k context window

202.1k tokens, estimated from the bundle at four bytes to the token — more than the whole window, so it cannot all be held at once: the model reads SKILL.md when the skill fires and the other files only as the instructions call for them. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

31 files, 808.2 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md26.9 kB
  • references/architecture.md69.2 kB
  • references/caching.md24.3 kB
  • references/conditions.md10.3 kB
  • references/config-app.md28.5 kB
  • references/config-bootstrap.md15.2 kB
  • references/config-general.md33.9 kB
  • references/config-general-extended.md29.4 kB
  • references/console-commands.md25.0 kB
  • references/controllers.md30.7 kB
  • references/cp.md68.5 kB
  • references/cp-components.md18.4 kB
  • references/cp-ui-patterns.md36.7 kB
  • references/debugging.md20.1 kB
  • references/deployment.md10.7 kB
  • references/drafts-revisions.md16.5 kB
  • references/element-authorization.md19.7 kB
  • references/element-index.md31.0 kB
  • references/elements.md54.1 kB
  • references/email.md13.7 kB
  • references/events.md29.0 kB
  • references/field-types-custom.md21.0 kB
  • references/fields.md18.7 kB
  • references/graphql.md22.3 kB
  • references/migrations.md27.0 kB
  • references/permissions.md31.0 kB
  • references/plugin-vite.md11.6 kB
  • references/quality.md25.1 kB
  • references/queue-jobs.md19.4 kB
  • references/sessions-and-auth.md17.6 kB
  • references/testing.md2.7 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 31 files you can review in full before installing. The MIT licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Craft CMS 5 — Extending (Plugins & Modules) · 202.1k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/craft-cms-5-extending-plugins-modules/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/craft-cms-5-extending-plugins-modules" ] && { [ ! -e .claude/skills/craft-cms-5-extending-plugins-modules ] || { mv .claude/skills/craft-cms-5-extending-plugins-modules "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/craft-cms-5-extending-plugins-modules" .claude/skills/ && echo "Installed .claude/skills/craft-cms-5-extending-plugins-modules"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add michtio/craft-cms-5-extending-plugins-modules

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/craft-cms-5-extending-plugins-modules/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/craft-cms-5-extending-plugins-modules/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/craft-cms-5-extending-plugins-modules" ] && { [ ! -e ~/.claude/skills/craft-cms-5-extending-plugins-modules ] || { mv ~/.claude/skills/craft-cms-5-extending-plugins-modules "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/craft-cms-5-extending-plugins-modules" ~/.claude/skills/ && echo "Installed ~/.claude/skills/craft-cms-5-extending-plugins-modules" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/craft-cms-5-extending-plugins-modules/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. It appears as craftcms in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, craft-cms-5-extending-plugins-modules.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referencemichtio/craft-cms-5-extending-plugins-modules

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

Reviews

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