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 rileyhilliard/claude-essentials --skill visualizing-with-mermaidgit clone --depth 1 https://github.com/rileyhilliard/claude-essentialsWrote 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/rileyhilliard/claude-essentials/visualizing-with-mermaid)<a href="https://agentmods.dev/skills/rileyhilliard/claude-essentials/visualizing-with-mermaid"><img src="https://agentmods.dev/badge/skills/rileyhilliard/claude-essentials/visualizing-with-mermaid/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/rileyhilliard/claude-essentials/visualizing-with-mermaid"><img src="https://agentmods.dev/badge/skills/rileyhilliard/claude-essentials/visualizing-with-mermaid.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 | $0.00037 | $0.00580 |
| Opus 5 | $0.00018 | $0.00290 |
| Sonnet 5 | $0.00007 | $0.00116 |
| Haiku 4.5 | $0.00004 | $0.00058 |
Grade A, and why
visualizing-with-mermaid 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- visualizing-with-mermaid — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mermaid Diagrams
Default: Dark mode colors from references/color-palettes.md.
Choosing Diagram Type
| Concept | Diagram Type |
|---|---|
| Process flows, decisions | Flowchart (TB direction) |
| API calls, message passing | Sequence diagram |
| Lifecycle states | State diagram |
| Data models, relationships | Class diagram or ERD |
| System architecture | Flowchart with subgraphs (LR direction) |
Core Principles
- Visual hierarchy over decoration - Color/size guide the eye to what matters
- Semantic color - Colors have meaning (grouping, state, criticality)
- Simplicity over completeness - 80% clearly beats 100% confusingly
- 7-12 nodes max - Human working memory limit; break larger systems into drill-downs
Quick Styling Guide
Do:
- Use fills to group related components
- Highlight critical paths with stroke width
- Different shapes = different component types (cylinders for DBs, diamonds for decisions)
- Keep labels to 1-4 words; use
<br/>for longer
Don't:
- Pure black (
#000000) - too harsh, use dark gray - Saturated background colors - tire the eyes
- More than 5 colors per diagram
- Low-contrast combinations
Shape Semantics
- Rectangles: Services, processes
- Rounded rectangles: APIs, interfaces
- Circles: Start/end points, external systems
- Diamonds: Decision points
- Cylinders: Databases
- Hexagons: Queues, message brokers
Layout
LR (left-to-right): Pipelines, architecture diagrams TB (top-to-bottom): Hierarchies, decision flows
Use subgraphs for: deployment boundaries, logical layers, team ownership, trust boundaries.
Resources
- Color palettes: See references/color-palettes.md
- Pattern examples: See references/examples.md for architecture, state machines, data flows, ERDs
Workflow
- Purpose - What decision/understanding should this enable?
- Type - Choose based on what you're showing
- Structure - Identify components, relationships, groupings
- Style - Apply semantic colors, highlight critical paths
- Review - Can someone understand it in 10 seconds?
What ships with it
2 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 · 69 lines · 37 tokens per session scan A 45fcc1d851f8
visualizing-with-mermaid is a skill published in the GitHub repository rileyhilliard/claude-essentials (128 stars, last pushed 22d ago), licensed MIT. It adds 37 tokens to every session and 580 once invoked, about $0.0002 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 2026-08-30.
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