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 majiayu000/spellbook --skill codexgit clone --depth 1 https://github.com/majiayu000/spellbookWrote 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/majiayu000/spellbook/codex)<a href="https://agentmods.dev/skills/majiayu000/spellbook/codex"><img src="https://agentmods.dev/badge/skills/majiayu000/spellbook/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/majiayu000/spellbook/codex"><img src="https://agentmods.dev/badge/skills/majiayu000/spellbook/codex.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Excessive Agency · line 56 Skill selects an external model or provider that may use a different account or billing plan than the operator expects. Undisclosed model switches can cause unexpected cost or quota consumption.Fix: Remove the model/provider override or disclose it prominently and require explicit operator approval before invoking an external coding CLI or billed model.
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 | $0.00038 | $0.02018 |
| Opus 5.5 | $0.00015 | $0.00807 |
| Sonnet 5.5 | $0.00008 | $0.00404 |
| Haiku 4.5 | $0.00004 | $0.00202 |
Grade A, and why
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 12d 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 — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codex Skill Guide
Operating Contract
- Run
codex --versionandcodex exec --helpfirst. Stop if Codex is unavailable, and only use flags shown by the installed CLI. - If the user did not specify a model or reasoning effort, use the installed default. Do not hardcode a model list; model names and supported reasoning levels change over time.
- Select the smallest sandbox needed:
--sandbox read-onlyfor inspection and--sandbox workspace-writefor requested local edits. Network access, extra writable roots, and broader modes are separate grants. - Assemble the command from supported options such as:
-m, --model <MODEL>--config model_reasoning_effort="<LEVEL>"--sandbox <read-only|workspace-write|danger-full-access>-C, --cd <DIR>--add-dir <DIR>--json--ephemeral--skip-git-repo-check--dangerously-bypass-approvals-and-sandbox
- Do not use
--skip-git-repo-checkby default. Use it only when the user explicitly asks to run outside a Git repository or has approved that boundary bypass for this command. - Do not use deprecated compatibility shortcuts such as
--full-auto; use the explicit sandbox shown by current help. - Preserve stderr. Keep it out of the parent context by writing it to a bounded artifact and reading only the exit status, short tail, or targeted diagnostics. Never redirect it to
/dev/null. - For automation, batch work, cost investigation, or any run that needs measured usage, add
--jsonand save stdout as JSONL. Read the final usage event and report input, cached input, output, and reasoning tokens when present. - Enforce a hard wall-clock timeout with the supervising runtime. Stop on non-zero exit or timeout; do not automatically retry an expensive run.
- When continuing a genuinely conversational task, use
codex exec resume --lastvia stdin. Do not resume a session for homogeneous record batches; start a fresh bounded--ephemeralrun per tranche so accumulated history is not resent on every model call.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 12d ago Changed · +2 lines 1175535f7b1f
- 1mo ago Changed · +69 lines 9ed445e66c0a
- 1mo ago First seen · 63 lines · 38 tokens per session scan A d8ec1a538ea3
codex is a skill published in the GitHub repository majiayu000/spellbook (288 stars, last pushed yesterday), licensed MIT. It adds 38 tokens to every session and 2,018 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 2026-08-30.
Other skills, from other repositories
cao-session-management
Find available CAO (CLI Agent Orchestrator) agent profiles, and talk to the conductor and worker terminals of a running CAO session, including unblocking a stuck worker. Use when choosing a profile to launch, messaging or unblocking workers, or diagnosing a stuck session. For preflight, launching, session commands…
pneuma-session
Instructions for renaming an active Pneuma session and replacing its default preview with a useful title and summary. A Pneuma session is one work area inside a larger project.
fast-resume
Search local coding-agent session history and identify safe resume commands. Use when the user asks to find, inspect, continue, or recover previous work from Claude Code, Codex, Pi, or another agent indexed by fast-resume.
workflow
A workflow skill for embedded-device projects that plans and runs building, flashing, debugging, observing, and diagnosis tasks.
lov-organize-storage
A storage-organization tool for surveying a whole drive or archive and planning a project-based folder layout. It can rename items within the same drive after confirmation, while keeping a mapping, log, and rollback script.
lov-finder-action
A generator for custom right-click actions in macOS Finder, the file manager on Apple computers.