Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add attentiondotnet/davidondrej-skills --skill codex-subagentgit clone --depth 1 https://github.com/attentiondotnet/davidondrej-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/attentiondotnet/davidondrej-skills/codex-subagent)<a href="https://agentmods.dev/skills/attentiondotnet/davidondrej-skills/codex-subagent"><img src="https://agentmods.dev/badge/skills/attentiondotnet/davidondrej-skills/codex-subagent/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/attentiondotnet/davidondrej-skills/codex-subagent"><img src="https://agentmods.dev/badge/skills/attentiondotnet/davidondrej-skills/codex-subagent.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00055 | $0.00966 |
| Opus 5 | $0.00028 | $0.00483 |
| Sonnet 5 | $0.00011 | $0.00193 |
| Haiku 4.5 | $0.00006 | $0.00097 |
Grade A, and why
codex-subagent scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
94% identical to codex-subagent — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codex CLI as a Subagent
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
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
OUT=$(mktemp /tmp/codex-out.XXXXXX)
codex exec \
--cd /path/to/repo \
--sandbox workspace-write \
--output-last-message "$OUT" \
"Full task prompt: goal, constraints, files to touch, definition of done." \
</dev/null
</dev/nullis MANDATORY when stdin is not a real terminal (background shells, scripts): codex treats open stdin as extra context and waits forever for EOF.- Codex sees NOTHING of your conversation. Put all context in the prompt: goal, relevant paths, constraints, and how to verify it's done.
- Long prompt? Pipe it via stdin instead:
codex exec [flags] - < /tmp/task.md. - Wrap the command in a background/Bash subagent if your host agent has one (Cursor: Task tool with a shell subagent) so Codex's verbose stream stays out of the parent context. Fallback: a plain background terminal.
- Runs take minutes and have no built-in timeout — background it and monitor.
- Optional:
-m <model>to override the model,--jsonfor JSONL event stream.
Collect results
cat "$OUT" # final message = the deliverable
git -C /path/to/repo status --short # see what Codex actually changed
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 97 lines · 55 tokens per session scan A 8ac837ec6ade
codex-subagent is a skill published in the GitHub repository attentiondotnet/davidondrej-skills (11 stars, last pushed 2mo ago), licensed MIT. It adds 55 tokens to every session and 966 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to codex-subagent, differing in 11 lines, and is treated as a copy.
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