Context Course

0. Welcome to the Context Course

1. Skills: Portable Knowledge for Code Agents

2. MCP: The Model Context Protocol

3. Plugins: Bundling Tools for Distribution

Unit 3: Plugins Plugin Anatomy Building Your Own Plugin Quiz 1: Plugin Fundamentals Using Plugins Quiz 2: Building and Distributing Plugins

4. Subagents: Orchestrating Multi-Agent Workflows

5. Hooks: Observing and Guarding the Agent Lifecycle

6. Bonus: Nano Harness — Build Your Own Agent

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Quiz 1: Plugin Fundamentals

Test your understanding of plugins, their anatomy, and how they differ across platforms.

Question 1: What is a plugin?

A plugin is a single reusable workflow, like calculating ROI A plugin is a collection of tools that provides standardized access to external APIs A plugin is a reusable extension surface; Claude Code and Codex use plugin bundles, while OpenCode plugins are code modules loaded from files or npm A plugin is a text file that describes how to use an agent tool

Question 2: What does plugin.json do?

For Claude Code and Codex, plugin.json tells the agent the plugin's identity and where to find bundled components plugin.json is just documentation describing what's in the plugin plugin.json is a list of all the API endpoints the plugin can access plugin.json is automatically generated and doesn't need to be written manually

Question 3: How do manifest-first plugins differ by platform?

Claude Code uses .claude-plugin/plugin.json; Codex uses .codex-plugin/plugin.json; both place skills/ at the plugin root All platforms use the exact same manifest.json format at the plugin root Only Codex supports plugin marketplaces Claude Code and Codex plugins are fully interchangeable

Question 4: How do skills and MCP servers fit inside a plugin?

In Claude Code and Codex, a plugin can only contain skills OR MCP servers, not both In Claude Code and Codex, skills are human-readable workflows; MCP servers provide programmatic tool access Skills and MCP servers do the same thing; you only need one Only Claude Code plugins use skills; Codex plugins only use MCP servers

Question 5: What can a Codex plugin reference?

The plugin manifest directory is always named .claude-plugin/ regardless of platform Codex plugins can reference MCP servers and app integrations via paths in plugin.json OpenCode uses a formal plugin manifest like Claude Code and Codex All plugins must have an MCP server to be useful

Summary

If you got 4-5 correct, you have a solid grasp of plugin anatomy. If you missed several, reread the introduction and anatomy lessons before moving on.

Key Takeaways

Plugins are a packaging surface, not the same thing as a skill or an MCP server
Claude Code and Codex use manifest-first plugins, while OpenCode uses code-first modules
On manifest-first platforms, plugin.json tells the agent where bundled components live

Next Steps

Next, use plugins in a real workflow and see how installation and activation differ by platform.

Update on GitHub

←Building Your Own Plugin Using Plugins→

Quiz 1: Plugin Fundamentals Question 1: What is a plugin?Question 2: What does plugin.json do?Question 3: How do manifest-first plugins differ by platform?Question 4: How do skills and MCP servers fit inside a plugin?Question 5: What can a Codex plugin reference?Summary Key Takeaways Next Steps