concepts/customization.md Codex Docs, 2026-03-27 18:23 UTC → 2026-05-01 18:29 UTC

5In Codex, customization comes from a few layers that work together:5In Codex, customization comes from a few layers that work together:

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7- **Project guidance (`AGENTS.md`)** for persistent instructions7- **Project guidance (`AGENTS.md`)** for persistent instructions

8- **[Memories](https://developers.openai.com/codex/memories)** for useful context learned from prior work

8- **Skills** for reusable workflows and domain expertise9- **Skills** for reusable workflows and domain expertise

9- **[MCP](https://developers.openai.com/codex/mcp)** for access to external tools and shared systems10- **[MCP](https://developers.openai.com/codex/mcp)** for access to external tools and shared systems

10- **[Subagents](https://developers.openai.com/codex/concepts/subagents)** for delegating work to specialized subagents11- **[Subagents](https://developers.openai.com/codex/concepts/subagents)** for delegating work to specialized subagents

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12These are complementary, not competing. `AGENTS.md` shapes behavior, skills package repeatable processes, and [MCP](https://developers.openai.com/codex/mcp) connects Codex to systems outside the local workspace.13These are complementary, not competing. `AGENTS.md` shapes behavior, memories

14carry local context forward, skills package repeatable processes, and

15[MCP](https://developers.openai.com/codex/mcp) connects Codex to systems outside the local workspace.

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14## AGENTS Guidance17## AGENTS Guidance

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57Use skill folders to author and iterate on workflows locally. If a plugin60Use skill folders to author and iterate on workflows locally. If a plugin

58already exists for the workflow, install it first to reuse a proven setup. When61already exists for the workflow, install it first to reuse a proven setup. When

59you want to distribute your own workflow across teams or bundle it with app62you want to distribute your own workflow across teams or bundle it with app

60integrations, package it as [plugins](https://developers.openai.com/codex/plugins). Skills remain the63integrations, package it as a [plugin](https://developers.openai.com/codex/plugins/build). Skills remain the

61authoring format; plugins are the installable distribution unit.64authoring format; plugins are the installable distribution unit.

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63A skill is typically a `SKILL.md` file plus optional scripts, references, and assets.66A skill is typically a `SKILL.md` file plus optional scripts, references, and assets.