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 ShibaInu0817/draw-c4-skill/plugin install draw-c4Wrote 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/shibainu0817/draw-c4-skill/draw-c4)<a href="https://agentmods.dev/skills/shibainu0817/draw-c4-skill/draw-c4"><img src="https://agentmods.dev/badge/skills/shibainu0817/draw-c4-skill/draw-c4/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/shibainu0817/draw-c4-skill/draw-c4"><img src="https://agentmods.dev/badge/skills/shibainu0817/draw-c4-skill/draw-c4.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 | $0.00180 | $0.03085 |
| Opus 5 | $0.00090 | $0.01543 |
| Sonnet 5 | $0.00036 | $0.00617 |
| Haiku 4.5 | $0.00018 | $0.00309 |
Grade A, and why
draw-c4 scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 243 lines — stays where its author put it; the contents beside it link to each section on GitHub.
draw-c4 — interactive C4 architecture diagrams
Turns a codebase into an explorable diagram: a single HTML file with no build step and no dependencies, holding up to four levels of detail and a set of animated runtime flows.
Find the skill directory first
Do this once, before any other step. This skill's files sit wherever it was
installed, which is never the user's working directory. Resolve that location and
use absolute paths from then on — bare relative paths like scripts/plot.py will
not resolve:
SKILL="$(dirname "$(dirname "$(find "${CLAUDE_PLUGIN_ROOT:-/nonexistent}" \
~/.claude/skills ~/.agents/skills "$PWD/.claude/skills" \
-name plot.py -path '*draw-c4*' 2>/dev/null | head -1)")")"
That covers every install route — plugin, npx skills, and a hand-copied skill
folder at user or project level. Sanity-check it resolved:
ls "$SKILL/scripts/plot.py" "$SKILL/assets/plot-template.html"
Every command below writes "$SKILL" for that directory. Keep the quotes; the
path can contain spaces. Read the bundled reference files by absolute path too —
$SKILL/references/model-schema.md, $SKILL/assets/example-model.json.
The model file and the output HTML are the user's, so those stay wherever the
user wants them, normally the repo being diagrammed. Never write into $SKILL.
Read $SKILL/references/model-schema.md for every field. Read
$SKILL/assets/example-model.json before writing a model — it is a complete,
hand-tuned example and imitating its level of specificity is most of the job.
How the pieces fit
The output file is two things welded together:
- The renderer —
$SKILL/assets/plot-template.html, about 700 lines of HTML, CSS and JS. It is fixed. It handles layout transforms, hit testing, the inspector, the flow player, keyboard shortcuts. Never edit it and never write it out by hand. - The model — one JSON object describing the system: levels, nodes, edges, flows. This is the only thing that varies between diagrams, and it is the only thing to write.
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.
- 10d ago First seen · 243 lines · 180 tokens per session scan A b5dd177ffac2
draw-c4 is a skill published in the GitHub repository ShibaInu0817/draw-c4-skill (2 stars, last pushed 7d ago), licensed MIT. It adds 180 tokens to every session and 3,085 once invoked, about $0.0009 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 2026-08-31.
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