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 HoangNguyen0403/agent-skills-standard --skill common-context-optimizationgit clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standardWrote 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/hoangnguyen0403/agent-skills-standard/common-context-optimization)<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/common-context-optimization"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/common-context-optimization/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/hoangnguyen0403/agent-skills-standard/common-context-optimization"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/common-context-optimization.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00040 | $0.00466 |
| Opus 5.5 | $0.00016 | $0.00186 |
| Sonnet 5.5 | $0.00008 | $0.00093 |
| Haiku 4.5 | $0.00004 | $0.00047 |
Grade A, and why
common-context-optimization 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 today.
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.
What it actually says
Priority: P1 (HIGH)
Workflow
- Inspect host capabilities; do not assume agents can rewrite history, prompts, or memory.
- Project outputs after consuming them: retain decisions, evidence, errors, and required values; point to complete logs/artifacts by stable reference.
- Bound context at host-supported boundaries. Carry goal, active slice, authority, decisions, blockers, evidence links, and next action; preserve a stable append-only prefix where supported.
- Compact only when useful and supported. Keep required details retrievable; never discard source evidence or rely on a fixed turn/token threshold.
- Measure cache reads, replayed input, and total actor cost across the whole task. Separate observed usage from estimates; no invoice, savings, or efficacy claims without evidence.
Anti-Patterns
- No history rewrite assumption: Project outputs or create artifact references; use only host-supported controls.
- No fixed threshold: Compact from observed context pressure and task needs, not a universal turn/token count.
- No evidence deletion: Keep stable references to source outputs, decisions, and verification. Archive required packets, reports and receipts at durable references before cleanup.
- No omission-as-optimization: Never claim savings from suppressing required instruction bodies. Selection or body-return counts are not acknowledgment, comprehension, or enforcement.
- No partial cost claim: Include cache reads, replay, and total actor cost; label estimates. Missing coverage or rates means no savings claim.
References
What ships with it
4 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.
- today Changed · +1 lines d58365f38068
- 19d ago Changed · -18 lines · -12 tokens per session e0756d938897
- 1mo ago First seen · 60 lines · 52 tokens per session scan A 0c292b0274a1
common-context-optimization is a skill published in the GitHub repository HoangNguyen0403/agent-skills-standard (583 stars, last pushed today), licensed MIT. It adds 40 tokens to every session and 466 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.
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