The uml skill helps you create PlantUML diagrams for software modeling, including class, sequence, activity, state machine, component, use case, deployment, and related diagrams. Use uml for Diagramming when you need editable, auto-laid-out, text-first diagrams for code, docs, and repo workflows. Not suited for layered architecture, charts, or BPMN workflows.
This skill scores 84/100, which means it is a solid listing candidate for directory users who want a ready-to-use UML/PlantUML workflow. The repository gives enough operational detail to trigger the skill correctly, understand the main diagram types, and produce diagrams with less guesswork than a generic prompt, though it is still somewhat documentation-heavy and would benefit from stronger adoption aids.
- Explicit trigger and scope: the frontmatter says it creates UML diagrams with PlantUML syntax and names the best-fit diagram families plus out-of-scope cases.
- Strong operational guidance: SKILL.md includes critical rules like @startuml/@enduml, required code fences, keyword and arrow syntax, and notes/styling guidance.
- Broad reusable coverage: the repo includes many concrete examples across common UML diagram types and a sizable stencil/examples library.
- No install command, scripts, or support files are provided, so users must rely on the markdown skill content alone.
- The repository is focused on diagram syntax and examples rather than interactive validation or workflow automation, which may limit reliability for complex edge cases.
Overview of uml skill
What uml skill does
The uml skill helps you turn a rough software idea into UML diagrams using PlantUML syntax. It is best for people who need a fast, text-first way to model classes, sequences, activities, states, components, deployment, use cases, and related relationships without drawing by hand.
Who it fits best
Use the uml skill if you are documenting code structure, system behavior, service boundaries, or a flow that needs to stay version-controlled in markdown. It is especially useful for developers, architects, technical writers, and AI agents generating diagram code for a repo or design doc.
When to choose it
Choose uml for Diagramming when the output should be precise, editable, and auto-laid out. It is a strong fit for dependency graphs, package hierarchies, and interaction flows. It is not the right skill for layered architecture diagrams, data visualization, or BPMN-style business workflows.
How to Use uml skill
Install and inspect the right files
Install the uml skill with npx skills add markdown-viewer/skills --skill uml. Then open SKILL.md first, followed by the example files that match your goal. The most useful starting points are examples/class-diagram.md, examples/sequence-diagram.md, examples/activity-diagram.md, and examples/deployment-diagram.md.
Give the model diagram intent, not just a topic
A weak prompt says, “Make a UML diagram for authentication.” A better uml usage prompt says what diagram type you need, what entities or actors must appear, and what relationship or flow should be shown. For example: “Create a sequence diagram for login with user, API, auth service, and database; include success and invalid-password branches.” That gives the skill enough structure to produce usable PlantUML.
Match input to the diagram type
The uml guide works best when you choose the right diagram up front. Use class diagrams for structure and inheritance, sequence diagrams for message flow, activity diagrams for branching workflows, state machines for lifecycle changes, component diagrams for service dependencies, and deployment diagrams for runtime placement. If you are unsure, inspect the matching examples/*.md file before prompting so your first output is closer to the intended notation.
Use the syntax constraints deliberately
PlantUML output should start with @startuml and end with @enduml, and fences should be ```plantuml or ```puml. Include this requirement in your prompt when you need a renderable result. If you want style consistency, ask for skinparam settings, named aliases, notes, or specific relationship arrows such as inheritance, composition, or dependency.
uml skill FAQ
Is uml skill beginner-friendly?
Yes, if you already know the business or system you want to diagram. The skill reduces syntax guesswork, but you still need to provide the diagram type, the main elements, and the relationships. Beginners get the best results when they start from one example file and adapt it rather than asking for a fully abstract diagram.
How is this different from a normal prompt?
A normal prompt may produce a vague diagram description. The uml skill is better for repeatable, renderable output because it is anchored in PlantUML syntax and specific UML conventions. That makes it more reliable for docs, reviews, and repo-based workflows where accuracy matters more than prose.
When should I not use uml?
Do not use uml skill if you need dashboard charts, business process notation, or broad architecture sketches that are better handled by another skill. It is also a poor fit when the goal is high-level brainstorming without fixed entities or relationships, because the syntax benefits from concrete inputs.
How to Improve uml skill
Give the diagram the facts that matter
The strongest uml install and usage results come from concrete inputs: names, roles, boundaries, key interactions, and the exact question the diagram should answer. For example, instead of “show my system,” say “show how a web client calls an API gateway, which routes to auth, orders, and billing services.” That improves layout, relationship choice, and overall usefulness.
Specify scope, not just content
A common failure mode is overstuffed diagrams. Improve the uml skill output by telling it what to leave out: “exclude internal helper classes,” “show only the happy path plus one error branch,” or “limit the component diagram to public interfaces.” This keeps the diagram readable and avoids unnecessary nodes.
Iterate from the first render
If the first diagram is too dense, ask for a narrower version, fewer labels, or a different diagram type. If the result is structurally right but visually messy, request naming cleanup, aliasing, or skinparam adjustments. If it misses meaning, add the missing relationship types or sequence steps and regenerate. The best uml guide workflow is usually two passes: structure first, styling second.