A skill for creating and checking Mermaid diagrams from text. Mermaid is a text-based format for diagrams such as flowcharts, sequence diagrams, database relationships, timelines, and architecture diagrams.

Use it to create or validate process flows, message sequences, schedules, class structures, state machines, database schemas, user journeys, and other supported diagrams.

It turns written descriptions into structured diagrams and catches common syntax problems before the diagrams are used.

mermaid — Skill for Claude Code and Codex by greedychipmunk

Install

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.

Any agent

npx skills add greedychipmunk/agent-skills --skill mermaid

Clone the repo

git clone --depth 1 https://github.com/greedychipmunk/agent-skills

Made for: Claude Code, Codex.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/greedychipmunk/agent-skills/mermaid/github.svg)](https://agentmods.dev/skills/greedychipmunk/agent-skills/mermaid)

Your own site

<a href="https://agentmods.dev/skills/greedychipmunk/agent-skills/mermaid"><img src="https://agentmods.dev/badge/skills/greedychipmunk/agent-skills/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/greedychipmunk/agent-skills/mermaid"><img src="https://agentmods.dev/badge/skills/greedychipmunk/agent-skills/mermaid.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 88 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,754 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

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	$0.00088	$0.04754
Opus 5	$0.00044	$0.02377
Sonnet 5	$0.00018	$0.00951
Haiku 4.5	$0.00009	$0.00475

Measured 10d ago against content hash 244690207e04, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

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.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

mermaid/SKILL.md · 451 lines

How it starts

The opening of the file, as written. The whole thing — 451 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Mermaid.js

Generate Mermaid.js diagrams from text descriptions and validate existing Mermaid syntax.

When to Use

Creating any of the 18 Mermaid diagram types from structured descriptions
Converting plain-language descriptions into visual diagrams
Validating existing Mermaid syntax for common errors
Choosing the right diagram type for a given scenario
Styling or theming Mermaid diagrams

Diagram Types at a Glance

Diagram	Keyword	Use For
Flowchart	`flowchart` / `graph`	Process flows, decision trees, system logic
Sequence	`sequenceDiagram`	Message passing between actors over time
Gantt	`gantt`	Project schedules, task timelines
Class	`classDiagram`	OOP class structure, inheritance, relationships
State	`stateDiagram-v2`	State machines, transitions, lifecycle
ER	`erDiagram`	Database schemas, entity relationships
Git Graph	`gitGraph`	Git branching and merge strategies
User Journey	`journey`	User experience across task steps
Quadrant	`quadrantChart`	2D prioritization (e.g. impact vs. effort)
XY Chart	`xychart-beta`	Bar charts, line charts with axes
Pie	`pie`	Proportional data, percentage breakdowns
Architecture	`architecture-beta`	Cloud/CI-CD service topology
Block	`block-beta`	Fixed-position block layouts
Requirement	`requirementDiagram`	SysML requirement traceability
Treemap	`treemap-beta`	Hierarchical proportional data
Mindmap	`mindmap`	Brainstorming, concept hierarchy
Timeline	`timeline`	Chronological events
Sankey	`sankey-beta`	Flow quantities between nodes

Universal Syntax

Every diagram begins with a diagram type keyword. Optional frontmatter and directives can configure the diagram before content.

Frontmatter

YAML between --- lines at the very start. Used for layout, look, and theme configuration.

---
config:
  layout: elk
  look: handDrawn
  theme: forest
---
flowchart LR
    A --> B

Read the full file on GitHub · 451 lines

Files

What ships with it

19 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.

Changes

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 · 451 lines · 88 tokens per session scan A 244690207e04

Subscribe to this mod's changes

mermaid is a skill published in the GitHub repository greedychipmunk/agent-skills (17 stars, last pushed 17d ago), licensed MIT. It adds 88 tokens to every session and 4,754 once invoked, about $0.0004 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.

Design and UX

webgl-holographic-foil

A self-contained WebGL2 hero: thin-film interference over a crushed-foil surface whose palette shifts with the viewing angle; move the cursor to tilt the film.

nexu-io/open-design · 41 tokens

html-ppt-hermes-cyber-terminal

OpenDesign + BYOK: choosing and wiring your own model, hands-on — cost, quality, and the routing decision. Built as a decision-grade AI literacy deck for engineers, IT, applied-AI teams.

nexu-io/open-design · 53 tokens

html-ppt-taste-brutalist

16:9 HTML deck in tactical-telemetry / CRT-terminal taste. Deactivated-CRT charcoal slides, white-phosphor monospace, hazard-red accent, scanline overlay, ASCII syntax, density over decoration. Distilled from Leonxlnx/taste-skill brutalist-skill (Tactical Telemetry mode).

nexu-io/open-design · 78 tokens

mermaid