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/luongnv89/asm/skill-shortenernpx skills add luongnv89/asm --skill skill-shortenergit clone --depth 1 https://github.com/luongnv89/asmWrote 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/luongnv89/asm/skill-shortener)<a href="https://agentmods.dev/skills/luongnv89/asm/skill-shortener"><img src="https://agentmods.dev/badge/skills/luongnv89/asm/skill-shortener.svg" alt="Measured on agentmods" 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 | $0.00058 | $0.03786 |
| Opus 5 | $0.00029 | $0.01893 |
| Sonnet 5 | $0.00012 | $0.00757 |
| Haiku 4.5 | $0.00006 | $0.00379 |
Grade E, and why
skill-shortener scanned grade E with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Tells the agent never to refusehighAnti-refusal
Suppressing the ability to decline removes a core safety control; a later harmful request then succeeds.
- **The user asks to cut a never-cut block** → say in one sentence why it stays, then pursue the size target through the other dispositions. Do not silently comply, and do not refuse the whole task. Recursive force deletehighDestructive command
rm -rf with a variable or a broad path is one typo away from removing the wrong tree.
rm -rf "$SKILL_PATH" && cp -R "$SNAP" "$SKILL_PATH" How it starts
The opening of the file, as written. The whole thing — 248 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Shortener
Shrink an over-long SKILL.md by progressive disclosure: what the agent needs on every activation stays in the body, everything else moves behind a pointer that says when to load it — or is cut outright.
Three load layers decide where a piece of content belongs:
| Layer | Holds | Costs |
|---|---|---|
| always-loaded | frontmatter name + description |
every turn |
| on-trigger | the SKILL.md body |
every activation |
| on-demand | references/, scripts/, assets/ |
only when read |
The bar is behavior-preserving: the shortened skill drives the same process as the long one. Line count is the score, not the goal — a run that reaches 400 lines by deleting a loop's stop condition has failed, however good the number looks.
Two modes
Pick one before Phase 0; they diverge at Phase 2.
- Mode 1 — shorten (default). Phases 0–4: measure, classify, plan, apply on approval, verify. Every "shorten this", "this SKILL.md is too long", "cut its token cost", "apply progressive disclosure" request is Mode 1.
- Mode 2 — audit only. Phases 0–2, then stop and hand over the plan. Nothing outside the workdir is written, so the repo sync and snapshot in Phase 0 are skipped. Use when the user wants to know what would move, or will apply the split themselves.
Run variables
Every snippet below uses these four. Bash tool calls do not share shell state, so re-declare them at the top of each call that needs them — an empty $SKILL_PATH turns cp -R "$SKILL_PATH/." into a copy of the filesystem root. Capture RUN_EPOCH once and reuse the number; never re-stamp it.
SS="$HOME/.claude/skills/skill-shortener" # this skill
SKILL_PATH="$HOME/.claude/skills/<target>" # the target: the dir holding SKILL.md
QV="$HOME/.claude/skills/skill-creator/scripts/quick_validate.py" # the Phase 4 gate
# RUN_EPOCH: reuse the number the preflight printed, e.g. RUN_EPOCH=1787948450
What ships with it
8 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.
- 6d ago First seen · 248 lines · 58 tokens per session scan E 3f8593f01ca7
skill-shortener is a skill published in the GitHub repository luongnv89/asm (913 stars, last pushed today), licensed MIT. It adds 58 tokens to every session and 3,786 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it E with 2 findings (tells the agent never to refuse, recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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