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 JayRHa/AgentSkills --skill mermaid-diagram-buildergit clone --depth 1 https://github.com/JayRHa/AgentSkillsWrote 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/jayrha/agentskills/mermaid-diagram-builder)<a href="https://agentmods.dev/skills/jayrha/agentskills/mermaid-diagram-builder"><img src="https://agentmods.dev/badge/skills/jayrha/agentskills/mermaid-diagram-builder/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/jayrha/agentskills/mermaid-diagram-builder"><img src="https://agentmods.dev/badge/skills/jayrha/agentskills/mermaid-diagram-builder.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 | $0.00144 | $0.01743 |
| Opus 5 | $0.00072 | $0.00872 |
| Sonnet 5 | $0.00029 | $0.00349 |
| Haiku 4.5 | $0.00014 | $0.00174 |
Grade A, and why
mermaid-diagram-builder 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 9d 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 — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mermaid Diagram Builder
Overview
Mermaid is a text-based diagramming language that renders to SVG. Because diagrams are plain text, they live in version control, diff cleanly in PRs, and render natively on GitHub, GitLab, Notion, Obsidian, VS Code, and most Markdown tools.
This skill helps you (1) pick the correct diagram type for the user's intent, (2) write valid, idiomatic Mermaid, (3) style it for clarity, and (4) verify it renders before delivering.
Keywords: mermaid, diagram, flowchart, sequence diagram, ER diagram, entity relationship, class diagram, state diagram, gantt, C4, architecture, diagram as code, graphviz alternative, markdown diagram.
Workflow
- Clarify intent. Determine what the user is modeling: a process/decision (flowchart), an interaction over time (sequence), a data model (ER), an object structure (class), lifecycle states (state), a schedule (gantt), or a system's components (C4/architecture). If ambiguous, ask one targeted question or pick the best fit and say why. See
references/diagram-types.mdfor the selection guide. - Choose the diagram type using the decision table in
references/diagram-types.md. - Draft the Mermaid code following the syntax patterns in
references/syntax-cheatsheet.md. Start with the header keyword (e.g.flowchart TD), then nodes/relationships, then styling last. - Apply clarity conventions (direction, concise labels, grouping with subgraphs, consistent node shapes). See Best Practices below.
- Validate the syntax. Run
scripts/validate_mermaid.py <file.mmd>for static checks, or use the Mermaid CLI (mmdc) if available to do a real render. Seescripts/validate_mermaid.py. - Deliver the diagram inside a fenced ```mermaid code block so it renders in Markdown. Offer a PNG/SVG export command if the user needs an image.
Choosing a diagram type (quick reference)
| User intent / phrase | Diagram type | Header keyword |
|---|---|---|
| "steps", "process", "decision", "if/else", "workflow" | Flowchart | flowchart TD |
| "API call", "request/response", "who talks to whom over time" | Sequence | sequenceDiagram |
| "database", "tables", "schema", "relationships", "foreign keys" | Entity Relationship | erDiagram |
| "classes", "objects", "OOP", "inheritance", "methods/attributes" | Class | classDiagram |
| "states", "lifecycle", "status transitions", "state machine" | State | stateDiagram-v2 |
| "timeline", "schedule", "project plan", "milestones" | Gantt | gantt |
| "system architecture", "services", "containers", "boundaries" | C4 / Architecture | C4Context / architecture-beta |
| "user journey", "experience steps with sentiment" | Journey | journey |
| "git branches", "commits", "merges" | Git graph | gitGraph |
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.
- 9d ago First seen · 86 lines · 144 tokens per session scan A d0415d744d13
mermaid-diagram-builder is a skill published in the GitHub repository JayRHa/AgentSkills (5 stars, last pushed 1mo ago), licensed MIT. It adds 144 tokens to every session and 1,743 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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