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 Avinava/document-design-system/plugin install document-design-systemWrote 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/avinava/document-design-system/diagram-design)<a href="https://agentmods.dev/skills/avinava/document-design-system/diagram-design"><img src="https://agentmods.dev/badge/skills/avinava/document-design-system/diagram-design.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 | $0.00139 | $0.02189 |
| Opus 5 | $0.00069 | $0.01094 |
| Sonnet 5 | $0.00028 | $0.00438 |
| Haiku 4.5 | $0.00014 | $0.00219 |
Grade A, and why
diagram-design 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 7d 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 — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Diagram Design
A diagram earns its place when the arrangement itself carries meaning that a sentence or a list cannot carry as fast.
That is the whole test. Boxes-and-arrows restating a numbered list is slower than the list. A flowchart of a linear three-step process is worse than three sentences. Before drawing anything, say what the reader will understand from the shape that they would not get from the prose.
If the answer is "nothing," write the prose.
The standard
The highest-quality move is usually deletion. Every node earns its place. Target density around 4/10 — a diagram that fills its frame is almost always doing too much.
The accent color is reserved for the one or two things the reader should look at first. Everything else is ink and hairlines.
(This standard is adapted from cathrynlavery/diagram-design, MIT. See Credits.)
Choosing a form
Match the form to the relationship being shown, not to the data you happen to have.
| The reader needs to understand | Form |
|---|---|
| How parts are arranged and what talks to what | Architecture / system map |
| How something moves through steps, with branches | Flow |
| Who calls whom, in what order, over time | Sequence |
| What states exist and what transitions between them | State machine |
| How entities relate and what they hold | Data model |
| What happened when, and in what order | Timeline |
| How responsibility is divided across actors | Swimlane |
| How options compare on two independent axes | Quadrant |
| What sits on top of what | Layer stack |
| How something narrows or concentrates | Funnel |
| How sets overlap | Venn |
| How one thing decomposes into parts | Tree / nested |
If the answer is "several of these," the diagram is doing too much. Split it. Two clear diagrams beat one complete one — a reader who has to decode a diagram has already lost the time the diagram was meant to save.
For per-form construction rules — what to label, where to place the accent, how to handle overflow — read references/diagram-families.md.
What ships with it
3 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.
- 7d ago First seen · 149 lines · 139 tokens per session scan A 78061c92147c
diagram-design is a skill published in the GitHub repository Avinava/document-design-system (2 stars, last pushed 12d ago), licensed MIT. It adds 139 tokens to every session and 2,189 once invoked, about $0.0007 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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