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 Tarekkharsa/agentstack --skill run-codexgit clone --depth 1 https://github.com/Tarekkharsa/agentstackWrote 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/tarekkharsa/agentstack/run-codex)<a href="https://agentmods.dev/skills/tarekkharsa/agentstack/run-codex"><img src="https://agentmods.dev/badge/skills/tarekkharsa/agentstack/run-codex/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/tarekkharsa/agentstack/run-codex"><img src="https://agentmods.dev/badge/skills/tarekkharsa/agentstack/run-codex.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 | $0.00054 | $0.00736 |
| Opus 5.5 | $0.00022 | $0.00294 |
| Sonnet 5.5 | $0.00011 | $0.00147 |
| Haiku 4.5 | $0.00005 | $0.00074 |
Grade A, and why
run-codex 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Run Codex (gpt-5.5)
Use this skill when you want to hand a well-specified chunk of work to gpt-5.5 (via OpenAI's Codex CLI) instead of doing it inline — because it's bulk/mechanical, or because you want a second, independent perspective on something that ships.
When to reach for Codex
- Bulk / mechanical work you can fully specify — migrations, codemods, repetitive refactors, large data or log analysis.
- An independent review — a second opinion on a diff or plan, from a different model than the one that wrote it.
- Not for taste-critical UI/copy/API design, or vague tasks you can't pin down — those stay with the orchestrating model.
Rule of thumb: if you can fully specify the task in the prompt, it's a good Codex job. If you can't specify it, don't delegate it.
Commands
# Investigate / review — read-only, cannot edit files:
codex exec -s read-only "<self-contained prompt>"
# Make edits — can modify the working tree:
codex exec "<self-contained prompt>"
# Review a diff — scope is required (bare `codex review` errors):
codex review --base <branch> # or --uncommitted, or --commit <sha>
Write self-contained prompts
Codex starts fresh — it does not see your conversation. Every prompt must carry its own context: the goal, the exact files/paths, the acceptance criteria, and any conventions that matter.
Codex reads AGENTS.md, not CLAUDE.md. If the project's conventions live
in CLAUDE.md (build/test commands, style, commit format), paste the relevant
ones into the prompt.
Timeouts
Codex runs can exceed a 10-minute command timeout. Pass an explicit longer timeout, or run it in the background and poll for its output / report file.
Parallel edits → isolate
If you run several editing Codex jobs at once, give each its own git worktree so their edits don't collide in the shared checkout.
Quota-aware fallback (important)
Codex access is usually a finite quota, not unlimited.
- On a usage-limit / quota / 429 error: do not retry — quota errors don't clear by retrying. Redo the task with a Claude model instead (clear-spec/mechanical → a small model; tricky, user-facing, or review work → a strong model).
- Once Codex reports a limit, treat it as exhausted for the session — stop routing new work to it, and tell the user, so they know the token mix shifted.
- A transient failure (network, timeout, malformed output) is different: one retry is fine before falling back.
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.
- 1mo ago First seen · 76 lines · 54 tokens per session scan A 31baf3662a47
run-codex is a skill published in the GitHub repository Tarekkharsa/agentstack (3 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 54 tokens to every session and 736 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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