codex-howto AGENTS.md

codex-howto AGENTS.md is an instructions file for Codex, OpenCode from Phelan164/codex-howto. It costs 285 tokens per session, scanned A, original, MIT.

Repository instructions for maintaining an engineering guide about OpenAI Codex, including editing rules and checks. AGENTS.md is a file that tells coding agents how to work in a repository.

In plain words
What is it for?
Use it when editing the guide to follow its repository rules, preserve sources, and run the required validation commands.
Why use it?
It keeps contributions consistent, accurate, safe, and aligned with the project’s definition of done.

Instructions file for CodexOpenCode

Install

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.

agentmods
npx agentmods add instructions/phelan164/codex-howto/agents-md
Clone the repo
git clone --depth 1 https://github.com/Phelan164/codex-howto

Made for: Codex, OpenCode.

Wrote 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.

agentmods badge for codex-howto AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/phelan164/codex-howto/agents-md.svg)](https://agentmods.dev/instructions/phelan164/codex-howto/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/phelan164/codex-howto/agents-md"><img src="https://agentmods.dev/badge/instructions/phelan164/codex-howto/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 285 This file is loaded in full into every session.
When invoked 285 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00285 $0.00285
Opus 5 $0.00143 $0.00143
Sonnet 5 $0.00057 $0.00057
Haiku 4.5 $0.00028 $0.00028

Measured 4d ago against content hash 87ffc129aba4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codex-howto AGENTS.md 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 4d 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.

AGENTS.md · 42 lines

What it actually says

Repository guidance

Purpose

Maintain an accurate, engineering-first learning guide for OpenAI Codex.

Editing rules

  • Keep product behavior aligned with official OpenAI documentation.
  • Label community practices and opinions clearly.
  • Do not add credentials, destructive examples, or full-access defaults.
  • Keep modules progressive: outcome, concepts, exercise, verification, sources.
  • Keep skill bodies concise; put optional detail in direct references/.
  • Preserve attribution to luongnv89/claude-howto as inspiration.
  • For work that depends on prior decisions, experiments, or established Codex guidance, read knowledge/index.md first and load only relevant pages.
  • Treat wiki queries as read-only unless the user explicitly requests capture, ingest, archive, or promotion.

Validation

Run:

python3 scripts/validate_repo.py
python3 skills/maintain-codex-wiki/scripts/wiki_lint.py .

For each changed skill, also run:

python3 /path/to/skill-creator/scripts/quick_validate.py skills/<skill-name>

Definition of done

  • All relative Markdown links resolve.
  • Every skill has valid frontmatter and UI metadata.
  • Living-wiki pages have registered sources and pass deterministic lint.
  • Examples are safe and contain no placeholder secrets.
  • Version-sensitive claims include an official source or verification note.
Changes

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.

  1. 4d ago First seen · 42 lines · 285 tokens per session scan A 87ffc129aba4

Subscribe to this mod's changes

codex-howto AGENTS.md is an instructions file published in the GitHub repository Phelan164/codex-howto (3 stars, last pushed 7d ago), licensed MIT. It adds 285 tokens to every session, about $0.0014 per session on Opus 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.