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Agent skill

Codex Subagent

by sickn33 in sickn33/agentic-awesome-skills

Launch Codex CLI as an isolated subagent for bounded coding, review, or verification tasks.

MITAuto-check passedAgent Workflows

Install Codex Subagent

skills CLI
$ npx skills add sickn33/agentic-awesome-skills --skill codex-subagent -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install sickn33/agentic-awesome-skills codex-subagent --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/sickn33/agentic-awesome-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/codex-subagent .claude/skills/codex-subagent && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
codex-subagent
GitHub stars
47k
Used in
1 other repo
Token cost
~1.1k tokens
SKILL.md length
474 words
Files
1
Skills in repo
1,394
Repo updated
First seen
Licence
MIT

At a glance

Launch Codex CLI as an isolated subagent for bounded coding, review, or verification tasks.

  • Tasks that involve Subagents
  • SKILL.md covers When to Use, When to delegate, Preflight and Launch, plus 6 more sections
  • Calls codex and git

What it does

Codex Subagent is an agent skill from sickn33/agentic-awesome-skills. Launch Codex CLI as an isolated subagent for bounded coding, review, or verification tasks.

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Agent Workflows, covering Subagents. The repository describes itself as: AAS Core is the local, agent-first control plane for complete catalog discovery, agent-owned selection, stack validation, and planning, backed by 2,400+ agentic skills. Includes… The licence is MIT.

When your agent uses it

  • Tasks that involve Subagents

Example prompts

  • “/codex-subagent”

Requirements

  • Node.js

What it can do on your machine

Read from SKILL.md and the folder at commit 1e53ce2. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • codex
    • git

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use git, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Codex Subagent loads about 1.1k tokens when it runs. Until then it costs about 27 tokens; SKILL.md has 474 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~27
When it runs · the whole SKILL.md, loaded when a task matches
~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from sickn33/agentic-awesome-skills at commit 1e53ce2, republished under its MIT licence (© sickn33). 474 words, ~1,142 tokens.

Download SKILL.mdSave it as .claude/skills/codex-subagent/SKILL.md (or your agent's skills folder).
name
codex-subagent
description
Launch Codex CLI as an isolated subagent for bounded coding, review, or verification tasks.
category
agent-orchestration
risk
critical
source
community
source_repo
davidondrej/skills
source_type
community
date_added
2026-07-07
author
davidondrej
tags
codex, subagents, delegation
tools
claude, codex
license
MIT

Codex CLI as a Subagent

When to Use

  • Use when a bounded coding, review, or verification task can run in a separate Codex CLI session.
  • Use when parallel work needs explicit file ownership and a clear definition of done.

Codex CLI is OpenAI's terminal coding agent. codex exec runs it non-interactively: it works autonomously in a sandbox, streams progress to stderr, and prints only the final message to stdout. Auth reuses the user's ChatGPT subscription — never an API key.

When to delegate

  • Self-contained coding task with clear success criteria (fix, feature, refactor, review).
  • Parallel work: several independent tasks at once (see Parallel runs).
  • Second opinion / independent verification of your own changes.

Do NOT delegate tasks that need conversation context you can't fully write into the prompt.

Preflight

bash
codex --version       # missing? npm i -g @openai/codex  (or: brew install --cask codex)
codex login status    # exit 0 + "Logged in using ChatGPT" = ready

Not logged in → stop and tell the user to run codex login (one-time browser OAuth). Never read, print, or copy credentials (~/.codex/auth.json).

Launch

bash
OUT=$(mktemp /tmp/codex-out.XXXXXX)
codex exec \
  --cd /path/to/repo \
  --sandbox workspace-write \
  --output-last-message "$OUT" \
  "Full task prompt: goal, constraints, files to touch, definition of done." \
  </dev/null
  • </dev/null is MANDATORY when stdin is not a real terminal (background shells, scripts): codex treats open stdin as extra context and waits forever for EOF.
  • Codex sees NOTHING of your conversation. Put all context in the prompt: goal, relevant paths, constraints, and how to verify it's done.
  • Long prompt? Pipe it via stdin instead: codex exec [flags] - < /tmp/task.md.
  • Wrap the command in a background/Bash subagent if your host agent has one (Cursor: Task tool with a shell subagent) so Codex's verbose stream stays out of the parent context. Fallback: a plain background terminal.
  • Runs take minutes and have no built-in timeout — background it and monitor.
  • Optional: -m <model> to override the model, --json for JSONL event stream.

Collect results

bash
cat "$OUT"                            # final message = the deliverable
git -C /path/to/repo status --short   # see what Codex actually changed

Follow-up in the same session (run from the same cwd — resume filters by cwd):

bash
codex exec resume --last "follow-up instruction" </dev/null
Show full SKILL.md (191 more words)Show less

Parallel runs

Parallelize only genuinely independent tasks, and assign file ownership upfront so results merge cleanly. One git worktree per Codex run — never two in the same tree:

bash
git worktree add /tmp/wt-taskA -b codex/task-a
codex exec --cd /tmp/wt-taskA --sandbox workspace-write -o /tmp/outA.md "task A" </dev/null

Failure modes

  • Hangs forever with no output → stdin was left open. Kill it, relaunch with </dev/null.
  • codex login status non-zero → the user must run codex login. Don't work around it.
  • ChatGPT plan rate limit hit → report to the user; never retry in a loop.
  • "Not a git repo" error → add --skip-git-repo-check, or init a repo first.
  • Network is blocked inside the workspace-write sandbox by default. If the task needs it (installs, API calls): -c sandbox_workspace_write.network_access=true.
  • NEVER use --dangerously-bypass-approvals-and-sandbox.

Rules

  • One task per launch. Split big jobs into multiple launches.
  • Review Codex's diff yourself before declaring the task done.

Cursor-native wrapper (optional)

For auto-routing and /codex invocation inside Cursor, add ~/.cursor/agents/codex.md — a custom subagent whose description is "delegates coding tasks to Codex CLI" and whose body points at this skill.

Limitations

  • Adapted from davidondrej/skills; verify local paths, tools, credentials, and agent features before acting.
  • For commands, remote access, scheduling, browser automation, or file-changing workflows, get explicit user approval and confirm the target environment first.

© sickn33, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/codex-subagent of sickn33/agentic-awesome-skills.

Open the folder on GitHubat commit 1e53ce2

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in sickn33/agentic-awesome-skills, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Codex Subagent next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Codex Subagent compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Codex Subagent this skillsickn33/agentic-awesome-skills47k1 repos~1.1kAutomated safety check: PassMIT
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Subagent Driven DevelopmentAsvarox/allkaraoke26137 repos~1.2kAutomated safety check: PassNone
Dispatching Parallel Agentsultralisp/ultralisp25840 repos~1.5kAutomated safety check: PassNone
Paseo Advisor Second Opiniongetpaseo/paseo20k1 repos~756Automated safety check: PassCustom licence
Task Observerrebelytics/one-skill-to-rule-them-all3.2k1 repos~12kAutomated safety check: PassCC-BY-4.0

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Categories

Questions about Codex Subagent

What does Codex Subagent do?

Launch Codex CLI as an isolated subagent for bounded coding, review, or verification tasks. Codex Subagent is an agent skill from sickn33/agentic-awesome-skills. Launch Codex CLI as an isolated subagent for bounded coding, review, or verification tasks.

When should I use Codex Subagent?

Codex Subagent fits situations like: tasks that involve Subagents.

How do I install Codex Subagent in Claude Code?

Run `npx skills add sickn33/agentic-awesome-skills --skill codex-subagent -a claude-code`. Or copy the skill folder (skills/codex-subagent in sickn33/agentic-awesome-skills) into .claude/skills/codex-subagent in your project. Claude Code loads it when a task matches its description.

How do I install Codex Subagent in Codex?

Run `npx skills add sickn33/agentic-awesome-skills --skill codex-subagent -a codex`. Or copy the skill folder (skills/codex-subagent in sickn33/agentic-awesome-skills) into .agents/skills/codex-subagent in your project. Codex loads it when a task matches its description.

Can I use Codex Subagent in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add sickn33/agentic-awesome-skills --skill codex-subagent -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/codex-subagent, .gemini/skills/codex-subagent, .github/skills/codex-subagent and .opencode/skills/codex-subagent in your project.

What does Codex Subagent need to run?

Going by SKILL.md and its folder, Codex Subagent needs the command-line tools its instructions call (codex and git). Our summary lists: Node.js.

Does Codex Subagent access the network?

SKILL.md contains no URLs. Its commands use git, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Codex Subagent safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Codex Subagent use?

Codex Subagent is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Codex Subagent use?

About 1.1k tokens (SKILL.md is roughly 4.6k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Codex Subagent?

Skills that share tags, products or a category with Codex Subagent: Claude Code Agent Development (anthropics/claude-plugins-official, 37k stars), Subagent Driven Development (Asvarox/allkaraoke, 261 stars), Dispatching Parallel Agents (ultralisp/ultralisp, 258 stars) and Paseo Advisor Second Opinion (getpaseo/paseo, 20k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Codex Subagent?

sickn33 (a GitHub user) maintains it in sickn33/agentic-awesome-skills, which has 47,304 GitHub stars. The repository holds 1,394 skills in this directory. The repository was last updated on October 6, 2026.

Source: sickn33/agentic-awesome-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.