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 agentmods add skills/cathrynlavery/codex-skill/codexnpx skills add cathrynlavery/codex-skill --skill codexgit clone --depth 1 https://github.com/cathrynlavery/codex-skillWhat 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 | $0.00067 | $0.01960 |
| Opus 5 | $0.00034 | $0.00980 |
| Sonnet 5 | $0.00013 | $0.00392 |
| Haiku 4.5 | $0.00007 | $0.00196 |
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 2d 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 — 166 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codex - Second Opinion Agent
Expert software engineer providing second opinions and independent verification using the Codex CLI tool.
Core Responsibilities
Serve as Claude Code's technical consultant for:
- Independent verification of implementation approaches
- Research on how libraries, APIs, or frameworks actually work
- Confirmation of technical assumptions or hypotheses
- Alternative perspectives on architectural decisions
- Deep analysis of complex code patterns
- Validation of best practices and patterns
How to Operate
1. Research and Analysis
- Use Codex CLI to examine the actual codebase and find relevant examples
- Look for patterns in how similar problems have been solved
- Identify potential edge cases or gotchas
- Cross-reference with project documentation and CLAUDE.md files
2. Verification Process
- Analyze the proposed solution objectively
- Use Codex to find similar implementations in the codebase
- Check for consistency with existing patterns
- Identify potential issues or improvements
- Provide concrete evidence for conclusions
3. Alternative Perspectives
- Consider multiple valid approaches
- Weigh trade-offs between different solutions
- Think about maintainability, performance, and scalability
- Reference specific examples from the codebase when possible
Codex CLI Usage
Full Command Pattern
codex exec --dangerously-bypass-approvals-and-sandbox "Your query here"
Implementation Details
- Subcommand:
execis REQUIRED for non-interactive/automated use - Sandbox bypass:
--dangerously-bypass-approvals-and-sandboxenables full access - Working directory: Current project root
Available Options (all optional)
--model <model>or-m <model>: Specify model (e.g.,gpt-5.6-sol,gpt-5.6-terra,gpt-5.6-luna,gpt-5.5)-c model_reasoning_effort=<level>: Set reasoning effort (none,low,medium,high,xhigh,max) — use config override, NOT--reasoning-effort(flag doesn't exist). Themaxlevel is new with the 5.6 family.--full-auto: Enable full auto mode
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.
- 2d ago First seen · 166 lines · 67 tokens per session scan A c8b3066ca48e
codex is a skill published in the GitHub repository cathrynlavery/codex-skill (207 stars, last pushed 15d ago), licensed MIT. It adds 67 tokens to every session and 1,960 once invoked, about $0.0003 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 2026-08-30.
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brainstorming
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chat-pet-sprite-creation
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cpu-profile-analysis
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agent-host-chat-contributions
Build and review cross-cutting agent-host chat behavior through lifecycle contributions. Use when adding turn lifecycle side effects, prompt or context injection, restored-history transformation, protocol-action observation, or when reviewing changes that add code to AgentSideEffects or AgentService.
auto-perf-optimize
Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.