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 stark-ai-de/agent-skills --skill codex-context-guardgit clone --depth 1 https://github.com/stark-ai-de/agent-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/stark-ai-de/agent-skills/codex-context-guard)<a href="https://agentmods.dev/skills/stark-ai-de/agent-skills/codex-context-guard"><img src="https://agentmods.dev/badge/skills/stark-ai-de/agent-skills/codex-context-guard/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/stark-ai-de/agent-skills/codex-context-guard"><img src="https://agentmods.dev/badge/skills/stark-ai-de/agent-skills/codex-context-guard.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 | $0.00065 | $0.00771 |
| Opus 5.5 | $0.00026 | $0.00308 |
| Sonnet 5.5 | $0.00013 | $0.00154 |
| Haiku 4.5 | $0.00006 | $0.00077 |
Grade A, and why
codex-context-guard 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 — 107 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codex Context Guard
Goal
Keep a long Codex session useful by reducing unnecessary context growth, preserving decisions in a compact handoff, and choosing bounded next steps before the thread becomes hard to continue.
Trigger conditions
- The task has many files, logs, diffs, generated outputs, or repeated tool calls.
- The user asks whether to compact, summarize, or continue in a new thread.
- The agent is about to inspect broad files without a specific need.
When to use
- Use when context budget, log volume, or file-reading scope is becoming a risk.
- Use before compacting a long session or moving work to another thread.
When not to use
- Do not use for short, self-contained tasks that have no context pressure.
- Do not use as a substitute for actually validating completed work.
Inputs to inspect
- Current objective, recent user instructions, changed files, validation output, and unresolved blockers.
- Use
git status --shortandgit diff --statbefore reading large diffs.
Rules
- Prefer targeted
rg,sed,git diff --stat, and small file ranges over whole-file dumps. - Keep one bounded objective active at a time.
- Store durable state in a handoff artifact when the work will outlive the current context.
- Summarize large outputs instead of pasting them back to the user.
- Tell the user when a compaction or handoff would preserve momentum.
Workflow
- Identify the current objective, latest decision, and next blocking question.
- Replace broad exploration with a targeted search plan.
- Track changed files, validation commands, and open risks in a compact note.
- Use references only when they solve the immediate context problem.
- When context is high, prepare a handoff and recommend
/compactor a new thread.
Commands
Useful low-context commands:
git diff --stat
git status --short
rg -n "pattern" path
sed -n '1,120p' path/to/file
Safety rules
- Do not hide failed validation behind a summary.
- Do not discard unresolved blockers when compacting.
- Do not paste secrets or full large logs into handoff text.
What ships with it
3 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.
- 1mo ago First seen · 107 lines · 65 tokens per session scan A 0d4444b1494f
codex-context-guard is a skill published in the GitHub repository stark-ai-de/agent-skills (8 stars, last pushed 3d ago), licensed Apache-2.0. It adds 65 tokens to every session and 771 once invoked, about $0.0003 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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