Codex

Skills and plugins

Understand skills, plugins and MCP; create reusable workflows and install capability packages.

Plugins, skills and MCP are related but distinct. First understand their roles, then choose the appropriate extension mechanism.

#How they relate

MechanismMeaningSolvesScopeAnalogyExamples
PluginInstallable capability packageDistribution and installationCan contain skills and toolsToolboxGitHub or Figma plugin
SkillReusable methodHow to perform a class of taskA workflowInstructions for the toolboxREADME or review skill
MCPExternal-tool protocolWhich tool/data to connectTool connectionPower connectionDatabase or docs MCP

Plugins can package skills and MCP. Skills define the method; MCP provides external operations and data.


#Skills

#What is a skill?

A skill defines a reusable workflow for tasks such as README generation, reviews or building a page. You invoke the saved workflow instead of repeating all instructions.

Create a skill when:

  • Similar tasks recur with many repeated requirements.
  • Consistent output or a shared team method matters.

Usually unnecessary: a one-off small edit, temporary wording change or simple factual question.

#Skill versus ordinary prompt

DimensionPromptSkill
InputWritten each timeSaved and invoked
ConsistencyEasy to omit requirementsReusable workflow
Suitable workOne-off taskRecurring task
ReuseLimitedHigh
ContentsInstructionsInstructions, templates, references and scripts

#Minimal SKILL.md

A skill needs a SKILL.md with name and description in frontmatter, followed by its workflow:

.agents/skills/readme-skill/SKILL.md
---
name: readme-skill
description: Use when generating a README, project overview, installation guide or startup instructions.
---

Create a beginner-friendly README for the current project.

Workflow:
1. Read the project structure.
2. Inspect package.json and entry points.
3. Identify the project type.
4. Write the overview, installation, startup commands, directory guide and FAQ.
5. Do not invent uncertain details.

Output format: Markdown.

The description helps determine when the skill applies. Name concrete trigger scenarios instead of a vague description such as “help with writing.”

Optional supporting directories:

.agents/skills/
└── readme-skill/
    ├── SKILL.md          required
    ├── scripts/          optional automation
    ├── references/       optional sources/templates
    └── assets/           optional examples

#Create and use a skill

Existing skills: browse available skills supplied by installed plugins.

Create a new skill:

1

Start a thread

Create a new conversation.

2

Invoke the creator

Use $skill-creator when available.

3

Describe the workflow

Explain its purpose, triggers, rules and an example output.

4

Review the result

Inspect SKILL.md and supporting files before saving and using it.

Skills in the desktop app

#Skill locations

ScopeLocationUse
Projectproject/.agents/skills/Repository-specific workflow
UserThe supported user skill directory, including ~/.codex/skills in this setupPersonal reusable workflow
TeamAdministrator/team distributionShared standards
PluginPackaged inside a pluginInstallable distribution

#Plugins

#What is a plugin?

A plugin packages specialized instructions, tools or connections. It can combine several skills and MCP definitions into one installable unit.

#Install and manage

1

Open Plugins

Search or browse the available catalog.

2

Install

Inspect the plugin details and choose Add to Codex where supported.

3

Use it

Start a new thread so the intended capabilities are available.

Plugin catalog

#Common capability categories

CategoryExamples
Browser/desktopChrome, Computer Use
Code collaborationGitHub
Frontend/designBuild Web Apps, Figma
DocumentsDocuments, Presentations, Spreadsheets
VideoHyperFrames, Remotion

The current catalog determines availability. Installed package access does not automatically grant every connected service's account permissions.


#Continue reading

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