mermaid

mermaid is a skill for Claude Code from eugeniosegala/claude-connoisseur. It costs 23 tokens per session (1,274 once invoked), scanned A, original, MIT.

A documentation tool that creates Mermaid diagrams, which are text-based diagrams rendered in Markdown, from a codebase. It can show architecture, data flows, class relationships, and other code structures.

In plain words
What is it for?
Use it to add accurate architecture diagrams, request flows, data pipelines, or class relationship diagrams to a README or other Markdown file.
Why use it?
It makes a project's structure easier to understand without drawing diagrams by hand or guessing how components connect.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

Part of the claude-connoisseur plugin — 13 skills, 2 hooks shipped together

Good fit Use it to add accurate architecture diagrams, request flows, data pipelines, or class relationship diagrams to a README or other Markdown file.

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

Made for: Claude Code.

Or install claude-connoisseur, the plugin that ships this one along with the rest of its 13 skills, 2 hooks.

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

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

agentmods 80×15 button for mermaid

Your own site · 80×15
<a href="https://agentmods.dev/skills/eugeniosegala/claude-connoisseur/mermaid"><img src="https://agentmods.dev/badge/skills/eugeniosegala/claude-connoisseur/mermaid.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,274 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.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00023 $0.01274
Opus 5 $0.00012 $0.00637
Sonnet 5 $0.00005 $0.00255
Haiku 4.5 $0.00002 $0.00127

Measured 12d ago against content hash 27ed03951c16, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, 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 12d 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.

skills/mermaid/SKILL.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Mermaid — Generate Mermaid Diagrams for the README

Generate clear, accurate Mermaid diagrams in the project README (or a specified Markdown file) to visualise architecture, data flows, class relationships, or other structures derived from the codebase.

Files and instructions: $ARGUMENTS

Core principles

Accuracy over aesthetics

  • Every element in the diagram must reflect the actual codebase. Do not invent components, connections, or flows that do not exist
  • Read the source files thoroughly before drawing anything. If a relationship is ambiguous, trace it in the code rather than guessing

Clarity and readability

  • Keep diagrams focused. A diagram that tries to show everything communicates nothing
  • Use meaningful node labels derived from actual file, function, class, or module names in the codebase
  • Prefer short, descriptive edge labels. Omit labels when the relationship is obvious from context
  • Group related nodes with subgraphs when it improves readability, but do not over-nest

Diagram type selection

Choose the Mermaid diagram type that best fits the subject:

  • flowchart (flowchart TD/LR) — request flows, pipelines, decision trees, process steps
  • sequence diagram (sequenceDiagram) — interactions between components over time (API calls, message passing)
  • class diagram (classDiagram) — class hierarchies, interfaces, type relationships
  • entity-relationship (erDiagram) — database schemas, data models, entity relationships
  • state diagram (stateDiagram-v2) — lifecycle states, state machines, status transitions
  • architecture (architecture-beta) — high-level system or infrastructure topology

If the user specifies a diagram type, use it. Otherwise, select the most appropriate one based on the code being visualised.

Integration with the README

  • Place the diagram in a logical section of the README. If a relevant section already exists, add the diagram there. If not, create a section with a clear heading
  • Use a fenced Mermaid code block (```mermaid) so the diagram renders natively on GitHub and other Markdown renderers
  • If the README already contains a Mermaid diagram for the same subject, update it rather than adding a duplicate

Read the full file on GitHub · 119 lines

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. 12d ago First seen · 119 lines · 23 tokens per session scan A 27ed03951c16

Subscribe to this mod's changes

mermaid is a skill published in the GitHub repository eugeniosegala/claude-connoisseur (9 stars, last pushed 4mo ago), licensed MIT. It adds 23 tokens to every session and 1,274 once invoked, about $0.0001 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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