concepts/customization.md Codex Docs, 2026-03-23 18:22 UTC → 2026-04-24 18:20 UTC

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

6 6 

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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54Skills are often the best fit for reusable workflows because they support richer instructions, scripts, and references while staying reusable across tasks.57Skills are often the best fit for reusable workflows because they support richer instructions, scripts, and references while staying reusable across tasks.

55Skills are loaded and visible to the agent (at least their metadata), so Codex can discover and choose them implicitly. This keeps rich workflows available without bloating context up front.58Skills are loaded and visible to the agent (at least their metadata), so Codex can discover and choose them implicitly. This keeps rich workflows available without bloating context up front.

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60Use skill folders to author and iterate on workflows locally. If a plugin

61already exists for the workflow, install it first to reuse a proven setup. When

62you want to distribute your own workflow across teams or bundle it with app

63integrations, package it as a [plugin](https://developers.openai.com/codex/plugins/build). Skills remain the

64authoring format; plugins are the installable distribution unit.

65 

57A 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.

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59- my-skill/68- my-skill/

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88Skills can be global (in your user directory, for you as a developer) or repo-specific (checked into `.agents/skills`, for your team). Put repo skills in `.agents/skills` when the workflow applies to that project; use your user directory for skills you want across all repos.97Skills can be global (in your user directory, for you as a developer) or repo-specific (checked into `.agents/skills`, for your team). Put repo skills in `.agents/skills` when the workflow applies to that project; use your user directory for skills you want across all repos.

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90| Layer | Global | repo |99| Layer | Global | Repo |

91| :----- | :--------------------- | :--------------------------------------------- |100| :----- | :--------------------- | :--------------------------------------------- |

92| AGENTS | `~/.codex/AGENTS.md` | `AGENTS.md` in repo root or nested directories |101| AGENTS | `~/.codex/AGENTS.md` | `AGENTS.md` in repo root or nested directories |

93| Skills | `$HOME/.agents/skills` | `.agents/skills` in repo |102| Skills | `$HOME/.agents/skills` | `.agents/skills` in repo |

145Build in this order:154Build in this order:

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1471. [Custom instructions with AGENTS.md](https://developers.openai.com/codex/guides/agents-md) so Codex follows your repo conventions. Add pre-commit hooks and linters to enforce those rules.1561. [Custom instructions with AGENTS.md](https://developers.openai.com/codex/guides/agents-md) so Codex follows your repo conventions. Add pre-commit hooks and linters to enforce those rules.

1482. [Skills](https://developers.openai.com/codex/skills) so you never have the same conversation twice. Skills can include a `scripts/` directory with CLI scripts or pair with [MCP](https://developers.openai.com/codex/mcp) for external systems.1572. Install a [plugin](https://developers.openai.com/codex/plugins) when a reusable workflow already exists. Otherwise, create a [skill](https://developers.openai.com/codex/skills) and package it as a plugin when you want to share it.

1493. [MCP](https://developers.openai.com/codex/mcp) when workflows need external systems (Linear, GitHub, docs servers, design tools).1583. [MCP](https://developers.openai.com/codex/mcp) when workflows need external systems (Linear, GitHub, docs servers, design tools).

1504. [Subagents](https://developers.openai.com/codex/subagents) when you're ready to delegate noisy or specialized tasks to subagents.1594. [Subagents](https://developers.openai.com/codex/subagents) when you're ready to delegate noisy or specialized tasks to subagents.