mermaid-skill

mermaid-skill is a skill for Claude Code, Codex from Agents365-ai/365-skills. It costs 137 tokens per session (3,204 once invoked), scanned B, original, no licence file.

A tool for writing Mermaid diagrams, which are diagrams described in text, and exporting them as image or document files. It supports formats such as flowcharts, sequence diagrams, class diagrams, and architecture diagrams.

In plain words
What is it for?
Creating and exporting flowcharts, sequence diagrams, class diagrams, ER diagrams, state machines, architecture diagrams, and Git graphs.
Why use it?
It lets you keep diagrams as editable text instead of drawing every element by hand. The diagrams can then be exported for sharing or documentation.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Creating and exporting flowcharts, sequence diagrams, class diagrams, ER diagrams, state machines, architecture diagrams, and Git graphs.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/agents365-ai/365-skills/mermaid-skill
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 Agents365-ai/365-skills --skill mermaid-skill
Clone the repo
git clone --depth 1 https://github.com/Agents365-ai/365-skills

Made for: Claude Code, Codex.

Its marketplace also offers this one on its own, as the plugin mermaid/plugin install mermaid after adding the marketplace above.

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.

agentmods badge for mermaid-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/agents365-ai/365-skills/mermaid-skill/github.svg)](https://agentmods.dev/skills/agents365-ai/365-skills/mermaid-skill)
Your own site
<a href="https://agentmods.dev/skills/agents365-ai/365-skills/mermaid-skill"><img src="https://agentmods.dev/badge/skills/agents365-ai/365-skills/mermaid-skill/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.

agentmods 80×15 button for mermaid-skill

Your own site · 80×15
<a href="https://agentmods.dev/skills/agents365-ai/365-skills/mermaid-skill"><img src="https://agentmods.dev/badge/skills/agents365-ai/365-skills/mermaid-skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 137 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,204 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00137 $0.03204
Opus 5 $0.00068 $0.01602
Sonnet 5 $0.00027 $0.00641
Haiku 4.5 $0.00014 $0.00320

Measured 7d ago against content hash 66f018dbf35c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade B, and why

mermaid-skill scanned grade B with 2 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.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/mermaid_live_link.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.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl -s -X POST -H "Content-Type: text/plain" --data-binary @diagram.mmd https://kroki.io/mermaid/svg -o /tmp/test.svg && echo "Valid" || echo "Invalid"

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl --version # Just need curl
plugins/mermaid/skills/mermaid-skill/SKILL.md · 239 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

10 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.

  1. 7d ago Changed · +4 lines · +13 tokens per session 66f018dbf35c
  2. 12d ago First seen · 235 lines · 124 tokens per session scan B 1d6e70b62a26

Subscribe to this mod's changes

mermaid-skill is a skill published in the GitHub repository Agents365-ai/365-skills (48 stars, last pushed yesterday), with no licence file. It adds 137 tokens to every session and 3,204 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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