concepts/customization.md Codex Docs, 2026-03-31 00:39 UTC → 2026-05-14 21:00 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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39Codex can load guidance from multiple locations: a global file in your Codex home directory (for you as a developer) and repo-specific files that teams can check in. Files closer to the working directory take precedence.42Codex can load guidance from multiple locations: a global file in your Codex home directory (for you as a developer) and repo-specific files that teams can check in. Files closer to the working directory take precedence.

40Use the global file to shape how Codex communicates with you (for example, review style, verbosity, and defaults), and keep repo files focused on team and codebase rules.43Use the global file to shape how Codex communicates with you (for example, review style, verbosity, and defaults), and keep repo files focused on team and codebase rules.

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42- ~/.codex/45<FileTree

43 46 class="mt-4"

44 - AGENTS.md Global (for you as a developer)47 tree={[

45- repo-root/48 {

46 49 name: "~/.codex/",

47 - AGENTS.md repo-specific (for your team)50 open: true,

51 children: [

52 { name: "AGENTS.md", comment: "Global (for you as a developer)" },

53 ],

54 },

55 {

56 name: "repo-root/",

57 open: true,

58 children: [

59 { name: "AGENTS.md", comment: "repo-specific (for your team)" },

60 ],

61 },

62 ]}

63/>

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49[Custom instructions with AGENTS.md](https://developers.openai.com/codex/guides/agents-md)65[Custom instructions with AGENTS.md](https://developers.openai.com/codex/guides/agents-md)

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63A skill is typically a `SKILL.md` file plus optional scripts, references, and assets.79A skill is typically a `SKILL.md` file plus optional scripts, references, and assets.

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65- my-skill/81<FileTree

66 82 class="mt-4"

67 - SKILL.md Required: instructions + metadata83 tree={[

68 - scripts/ Optional: executable code84 {

69 - references/ Optional: documentation85 name: "my-skill/",

70 - assets/ Optional: templates, resources86 open: true,

87 children: [

88 { name: "SKILL.md", comment: "Required: instructions + metadata" },

89 { name: "scripts/", comment: "Optional: executable code" },

90 { name: "references/", comment: "Optional: documentation" },

91 { name: "assets/", comment: "Optional: templates, resources" },

92 ],

93 },

94 ]}

95/>

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72The skill directory can include a `scripts/` folder with CLI scripts that Codex invokes as part of the workflow (for example, seed data or run validations). When the workflow needs external systems (issue trackers, design tools, docs servers), pair the skill with [MCP](https://developers.openai.com/codex/mcp).97The skill directory can include a `scripts/` folder with CLI scripts that Codex invokes as part of the workflow (for example, seed data or run validations). When the workflow needs external systems (issue trackers, design tools, docs servers), pair the skill with [MCP](https://developers.openai.com/codex/mcp).

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