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 onfire7777/universal-ai-skills-library --skill anvilgit clone --depth 1 https://github.com/onfire7777/universal-ai-skills-libraryWrote 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/onfire7777/universal-ai-skills-library/anvil)<a href="https://agentmods.dev/skills/onfire7777/universal-ai-skills-library/anvil"><img src="https://agentmods.dev/badge/skills/onfire7777/universal-ai-skills-library/anvil/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/onfire7777/universal-ai-skills-library/anvil"><img src="https://agentmods.dev/badge/skills/onfire7777/universal-ai-skills-library/anvil.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 | $0.00053 | $0.02570 |
| Opus 5 | $0.00026 | $0.01285 |
| Sonnet 5 | $0.00011 | $0.00514 |
| Haiku 4.5 | $0.00005 | $0.00257 |
Grade A, and why
anvil 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 9d 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 — 136 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Anvil
Trigger Guidance
Use Anvil for terminal-first work: CLI command design, TUI components, shell completion, doctor commands, toolchain wiring, config loading, environment checks, packaging, and cross-platform terminal behavior. Route adjacent work by default: pure business logic without a CLI contract → Builder · CI/CD or environment automation after the CLI contract is fixed → Gear · CLI test coverage and regression harnesses → Radar · user-facing documentation beyond help text and inline UX → Quill
Core Contract
- Build self-documenting CLIs:
--helpis part of the product, not an afterthought. - Deliver dual-mode output: human-readable by default, machine-readable via
--json. - Treat exit codes as contracts and keep stdout/stderr separation reliable.
- Stay TTY-aware: colors, prompts, animations, and progress displays must degrade cleanly in pipes and CI.
- Keep business logic outside CLI/TUI presentation layers.
- Cover CLI design, TUI components, tool integration, environment checks, cross-platform behavior, shell completion, and project scaffolding.
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.
- references/cli-design-anti-patterns.md 8.7 KB
- references/cli-design-patterns.md 10 KB
- references/cross-platform.md 9.1 KB
- references/distribution-packaging-anti-patterns.md 8.3 KB
- references/tool-integration-anti-patterns.md 7.9 KB
- references/tool-integration.md 6.7 KB
- references/tui-components.md 5.3 KB
- references/tui-ux-anti-patterns.md 8.2 KB
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.
- 9d ago First seen · 136 lines · 53 tokens per session scan A c7ebaf25003d
anvil is a skill published in the GitHub repository onfire7777/universal-ai-skills-library (16 stars, last pushed yesterday), licensed MIT. It adds 53 tokens to every session and 2,570 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 2026-09-03.
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