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/bntvllnt/agent-skills/skill-buildernpx skills add bntvllnt/agent-skills --skill skill-buildergit clone --depth 1 https://github.com/bntvllnt/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/bntvllnt/agent-skills/skill-builder)<a href="https://agentmods.dev/skills/bntvllnt/agent-skills/skill-builder"><img src="https://agentmods.dev/badge/skills/bntvllnt/agent-skills/skill-builder.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 | $0.00050 | $0.02192 |
| Opus 5 | $0.00025 | $0.01096 |
| Sonnet 5 | $0.00010 | $0.00438 |
| Haiku 4.5 | $0.00005 | $0.00219 |
Grade C, and why
skill-builder scanned grade C with 1 finding 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.
Recursive force deletehighDestructive command
rm -rf with a variable or a broad path is one typo away from removing the wrong tree.
- Never recommend `rm -rf`, `git reset --hard`, or `push --force` as defaults. How it starts
The opening of the file, as written. The whole thing — 296 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Builder
Unified, security-first skill builder.
This skill is intentionally opinionated:
- Prefer no new skill if a simpler change works.
- When you do create a skill, make it boring, testable, and hard to misuse.
- Keep one clear router and avoid overlapping descriptions across skills.
- Stay model-agnostic and harness-agnostic unless the target environment explicitly requires otherwise.
Operation Router
| User intent | Operation | Output |
|---|---|---|
| create/build/make/new skill | CREATE | new skill folder + SKILL.md + only the companion files actually needed |
| update/modify/improve skill | UPDATE | minimal diff, keep scope stable |
| delete/remove skill | DELETE | remove skill + update any dependent references |
| add content/route/workflow to skill | ADD | new router row + minimal supporting procedure |
| validate skill | VALIDATE | evidence-backed validation report + fixes |
| rename skill | RENAME | safe rename + reference updates |
Operation Selection Rules
Use the smallest operation that solves the request:
- CREATE — new user-facing capability or clearly distinct intent/description domain.
- UPDATE — improve an existing skill without changing its core scope.
- ADD — add one new route, example, or sub-workflow inside the current scope.
- RENAME — change identity/path/name while preserving mostly the same behavior.
- DELETE — remove obsolete capability because it is superseded, merged, or no longer useful.
- VALIDATE — inspect correctness without broadening scope.
If uncertain, default to UPDATE rather than CREATE.
What "Correct" Means
This skill treats "correct" as:
- Conforms to the Agent Skills spec where the spec is explicit.
- Uses progressive disclosure: concise
SKILL.md, deeper docs only when needed. - Has unambiguous activation: specific description + non-overlapping neighboring skills.
- Is safe: no secrets, no default-destructive commands, explicit confirmation boundaries.
- Produces validation evidence instead of relying on vibes.
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.
- 6d ago First seen · 296 lines · 50 tokens per session scan C a07f32412264
skill-builder is a skill published in the GitHub repository bntvllnt/agent-skills (16 stars, last pushed 3mo ago), licensed MIT. It adds 50 tokens to every session and 2,192 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 1 finding (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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