staruml-mdj-class-diagram

staruml-mdj-class-diagram is a skill for Claude Code, Codex from ChinaIceF/staruml-skills. It costs 73 tokens per session (2,896 once invoked), scanned A, original, MIT.

A tool for creating, inspecting, and safely changing StarUML class diagrams stored in .mdj files. Class diagrams show classes and relationships such as associations and inheritance.

In plain words
What is it for?
Use it to add or change classes, attributes, operations, associations, dependencies, and generalizations, or to automatically arrange a class diagram.
Why use it?
It avoids manually editing StarUML’s complex JSON-like diagram structure, reducing the risk of broken references and invalid files.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions OpenCode.

Good fit Use it to add or change classes, attributes, operations, associations, dependencies, and generalizations, or to automatically arrange a class diagram.

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Install with agentmods
npx agentmods add skills/chinaicef/staruml-skills/staruml-mdj-class-diagram
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 ChinaIceF/staruml-skills --skill staruml-mdj-class-diagram
Clone the repo
git clone --depth 1 https://github.com/ChinaIceF/staruml-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.

agentmods badge for staruml-mdj-class-diagram

README.md
[![agentmods](https://agentmods.dev/badge/skills/chinaicef/staruml-skills/staruml-mdj-class-diagram/github.svg)](https://agentmods.dev/skills/chinaicef/staruml-skills/staruml-mdj-class-diagram)
Your own site
<a href="https://agentmods.dev/skills/chinaicef/staruml-skills/staruml-mdj-class-diagram"><img src="https://agentmods.dev/badge/skills/chinaicef/staruml-skills/staruml-mdj-class-diagram/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 staruml-mdj-class-diagram

Your own site · 80×15
<a href="https://agentmods.dev/skills/chinaicef/staruml-skills/staruml-mdj-class-diagram"><img src="https://agentmods.dev/badge/skills/chinaicef/staruml-skills/staruml-mdj-class-diagram.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,896 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 $0.00073 $0.02896
Opus 5 $0.00036 $0.01448
Sonnet 5 $0.00015 $0.00579
Haiku 4.5 $0.00007 $0.00290

Measured 12d ago against content hash 78d70bfc2b8b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

staruml-mdj-class-diagram 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.

The scan reads SKILL.md. This mod also ships 7 executable files (examples/create_class_diagram.py, examples/modify_existing_diagram.py, staruml_tool/__init__.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.

staruml-mdj-class-diagram/SKILL.md · 257 lines

How it starts

The opening of the file, as written. The whole thing — 257 lines — stays where its author put it; the contents beside it link to each section on GitHub.

StarUML MDJ Class Diagram Skill

Purpose

This skill enables safe creation, inspection, and modification of StarUML .mdj files that contain UML Class Diagrams. The .mdj format is a deeply nested JSON document with intricate cross-references (_id, $ref, _parent, model, source, target, ownedElements, ownedViews). Manually editing this JSON is error-prone. This skill wraps the staruml_tool Python package to provide safe, high-level APIs and CLI commands.

Always use staruml_tool rather than editing .mdj JSON directly.

When to Use This Skill

  • Create a new StarUML .mdj class diagram from scratch.
  • Add, remove, or rename UML classes in an existing .mdj.
  • Add or remove attributes and operations on classes.
  • Add or remove associations (undirected or directed), generalizations, or dependencies.
  • Inspect an existing .mdj to understand its class layout, relationships, and connectivity.
  • Generate a UML class diagram from natural language requirements or code structure descriptions.
  • Auto-layout a class diagram to improve visual readability.

Do Not Use This Skill When

  • The user asks for sequence diagrams, use case diagrams, activity diagrams, statechart diagrams, component diagrams, deployment diagrams, package diagrams, or object diagrams. None of these are supported. Clearly state: "This skill only supports UML Class Diagrams."
  • The user requires precise font, color, line style, or visual styling control. The tool does not expose high-level styling APIs.
  • The .mdj file is corrupted and cannot be parsed as valid JSON.
  • The user needs true UMLInterface API, UMLEnumeration literal editing, UMLPackage, UMLComponent, UMLNode, or UMLConstraint manipulation. These model element types are not exposed via high-level API.

Supported Scope

Model elements with high-level API:

  • UMLClass (create, rename, delete, query)
  • UMLAttribute (add, remove per class)
  • UMLOperation (add, remove per class; parameters supported)
  • UMLParameter (created automatically with operations)

Read the full file on GitHub · 257 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 · 257 lines · 73 tokens per session scan A 78d70bfc2b8b

Subscribe to this mod's changes

staruml-mdj-class-diagram is a skill published in the GitHub repository ChinaIceF/staruml-skills (5 stars, last pushed 3mo ago), licensed MIT. It adds 73 tokens to every session and 2,896 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 2026-08-31.

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