Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add melodic-software/claude-code-plugins/plugin install animationWrote 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/melodic-software/claude-code-plugins/check-prerequisites)<a href="https://agentmods.dev/skills/melodic-software/claude-code-plugins/check-prerequisites"><img src="https://agentmods.dev/badge/skills/melodic-software/claude-code-plugins/check-prerequisites/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/melodic-software/claude-code-plugins/check-prerequisites"><img src="https://agentmods.dev/badge/skills/melodic-software/claude-code-plugins/check-prerequisites.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 | $0.00082 | $0.00360 |
| Opus 5.5 | $0.00033 | $0.00144 |
| Sonnet 5.5 | $0.00016 | $0.00072 |
| Haiku 4.5 | $0.00008 | $0.00036 |
Grade A, and why
check-prerequisites scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Purpose
Run the read-only check. Do not install anything, and do not edit prerequisites.json.
The plugin has no check skill, so the prerequisites check has its own name. A hook notice names it.
Check
Run the shared checker through its stub, which reports a missing node instead of failing to start:
sh "${CLAUDE_PLUGIN_ROOT}/lib/prerequisites.sh" check "${CLAUDE_PLUGIN_ROOT}" --data-dir "${CLAUDE_PLUGIN_DATA}"
Where there is no sh (Windows without Git Bash), run the PowerShell stub with the same arguments instead:
powershell -NoProfile -ExecutionPolicy Bypass -File "${CLAUDE_PLUGIN_ROOT}/lib/prerequisites.ps1" check "${CLAUDE_PLUGIN_ROOT}" --data-dir "${CLAUDE_PLUGIN_DATA}"
Report the PASS/FAIL rows as a table. On a FAIL, give the install hints the checker printed. Stop.
Next
/animation:setup
Gotchas
This skill does not install. A hook notice is not permission to install Node.js.
What ships with it
1 file 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.
- 12d ago First seen · 39 lines · 82 tokens per session scan A 796476898293
check-prerequisites is a skill published in the GitHub repository melodic-software/claude-code-plugins (25 stars, last pushed today), licensed MIT. It adds 82 tokens to every session and 360 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 2026-10-04.
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