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 xobotyi/cc-foundry --skill diagramminggit clone --depth 1 https://github.com/xobotyi/cc-foundryWrote 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/xobotyi/cc-foundry/diagramming)<a href="https://agentmods.dev/skills/xobotyi/cc-foundry/diagramming"><img src="https://agentmods.dev/badge/skills/xobotyi/cc-foundry/diagramming/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/xobotyi/cc-foundry/diagramming"><img src="https://agentmods.dev/badge/skills/xobotyi/cc-foundry/diagramming.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00056 | $0.02189 |
| Opus 5.5 | $0.00022 | $0.00876 |
| Sonnet 5.5 | $0.00011 | $0.00438 |
| Haiku 4.5 | $0.00006 | $0.00219 |
Grade A, and why
diagramming 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 1mo 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 — 217 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Diagramming
Understandable first, beautiful second. Every diagram exists to communicate — if it fails to communicate, aesthetics are irrelevant. When both are achievable, pursue both.
References
- Visual design principles — [
${CLAUDE_SKILL_DIR}/references/design-principles.md] Gestalt principles, grid system, spacing rules, color palette, typography, complexity budgets, anti-patterns, Tufte's data-ink principle - Excalidraw format — [
${CLAUDE_SKILL_DIR}/references/excalidraw.md] JSON schema, element types, styling properties, arrow binding, layout templates (linear, grid, radial, tiered, decision tree), diagram type conventions - Mermaid syntax — [
${CLAUDE_SKILL_DIR}/references/mermaid.md] Flowchart, sequence, class, state, ER diagram syntax, theming, per-node styling, subgraphs
Format Selection
Choose the format that matches the delivery context:
Use Mermaid when:
- The diagram lives in markdown (README, design doc, PR description, wiki)
- Auto-layout is acceptable — precise element positioning is not required
- The diagram type maps to a Mermaid-supported type
- Version-control readability matters (text diffs)
- Quick iteration speed matters more than visual refinement
Use Excalidraw when:
- Precise spatial layout is needed (architecture diagrams with specific grouping)
- The diagram needs freeform elements that don't fit a standard type
- Visual polish matters — color coding, consistent spacing, professional appearance
- The diagram will be used in presentations, external documentation, or design reviews
- The diagram needs to be manually editable after generation
Core Design Rules
These rules apply to every diagram regardless of format. They are non-negotiable.
- Consistent shapes — same concept type uses the same shape everywhere in the diagram. All services are rectangles. All databases are cylinders. All decisions are diamonds. Never vary shapes for the same concept.
- Consistent flow direction — pick one direction (top-to-bottom or left-to-right) and maintain it for all relationships of the same type within the diagram.
- Semantic color — color encodes meaning (tier, status, domain), never decoration. Maximum 2–3 accent colors per diagram. Use the semantic palette from the design-principles reference.
- Label everything that isn't obvious — every arrow in a complex diagram gets a label. Every color gets a legend entry. If a reader has to guess what something means, the diagram has failed.
- Whitespace is structure — group related elements tightly, separate groups with 2x the intra-group gap. When in doubt, add more space.
- Complexity budget — if a diagram exceeds 20 elements, split it. Create a high-level overview + detail diagrams. No exceptions.
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.
- 1mo ago First seen · 217 lines · 56 tokens per session scan A 1f713f15663a
diagramming is a skill published in the GitHub repository xobotyi/cc-foundry (23 stars, last pushed today), licensed MIT. It adds 56 tokens to every session and 2,189 once invoked, about $0.0002 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 2026-09-04.
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