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Agent skill

Use Case Diagram

by AI-Unified-Process in AI-Unified-Process/marketplace

Creates or updates PlantUML use case diagrams defining actors, use cases, and their relationships from requirements.

Apache-2.0Auto-check passedDevelopment

Install Use Case Diagram

skills CLI
$ npx skills add AI-Unified-Process/marketplace --skill use-case-diagram -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install AI-Unified-Process/marketplace use-case-diagram --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/AI-Unified-Process/marketplace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/aiup-core/skills/use-case-diagram .claude/skills/use-case-diagram && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
use-case-diagram
GitHub stars
142
Token cost
~1.1k tokens
SKILL.md length
548 words
Files
1
Skills in repo
14
Repo updated
First seen
Licence
Apache-2.0

At a glance

Creates or updates PlantUML use case diagrams defining actors, use cases, and their relationships from requirements.

  • Works in 6 steps: Read the requirements at… → Read existing diagram at… → Identify actors and use cases from… → …
  • The user asks to create a use case diagram
  • SKILL.md covers Instructions, DO NOT, Template and Goal level, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Use Case Diagram is an agent skill from AI-Unified-Process/marketplace. Creates or updates PlantUML use case diagrams defining actors, use cases, and their relationships from requirements. Use when the user asks to "create a use case diagram", "draw a UML diagram", "map actors to use cases", "generate a .puml file", or mentions PlantUML, use case overview, actor diagram, or system use cases.

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering Diagrams. The licence is Apache-2.0.

When your agent uses it

  • The user asks to create a use case diagram
  • Draw a UML diagram
  • Map actors to use cases
  • Generate a .puml file

Example prompts

  • “create a use case diagram”
  • “draw a UML diagram”
  • “map actors to use cases”
  • “/use-case-diagram”

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

  1. Read the requirements at docs/requirements.md
  2. Read existing diagram at docs/use_cases.puml (if exists)
  3. Identify actors and use cases from requirements
  4. Check every use case against the question in "Goal level": fold subfunctions into the user goal they serve,
  5. Create/update the PlantUML use case diagram
  6. Validate the diagram

What it can do on your machine

Read from SKILL.md and the folder at commit d25bf91. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are plantuml).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • unifiedprocess.ai

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Use Case Diagram loads about 1.1k tokens when it runs. Until then it costs about 85 tokens; SKILL.md has 548 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~85
When it runs · the whole SKILL.md, loaded when a task matches
~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from AI-Unified-Process/marketplace at commit d25bf91, republished under its Apache-2.0 licence (© AI-Unified-Process). 548 words, ~1,102 tokens.

Download SKILL.mdSave it as .claude/skills/use-case-diagram/SKILL.md (or your agent's skills folder).
name
use-case-diagram
description
Creates or updates PlantUML use case diagrams defining actors, use cases, and their relationships from requirements. Use when the user asks to "create a use case diagram", "draw a UML diagram", "map actors to use cases", "generate a .puml file", or mentions PlantUML, use case overview, actor diagram, or system use cases.
<!--
Copyright 2025-2026 Simon Martinelli and the AI Unified Process contributors.
Part of the AI Unified Process — https://unifiedprocess.ai
Licensed under the Apache License, Version 2.0. See LICENSE and NOTICE.
-->

Use Case Diagram

Instructions

Create or update the PlantUML use case diagram at docs/use_cases.puml based on docs/requirements.md.

DO NOT

  • Create diagrams without reading the requirements first
  • Use non-standard PlantUML syntax
  • Include implementation details in use case names
  • Model technical steps such as validating, loading, or persisting data as separate use cases (see "Goal level")

Template

plantuml
@startuml Use Cases Overview
left to right direction

actor "User" as user
actor "Administrator" as admin

rectangle "System Name" {
    usecase "UC-001\nDescription" as UC001
    usecase "UC-002\nDescription" as UC002
    usecase "UC-003\nDescription" as UC003
}

admin --> UC001
user --> UC002
user --> UC003

@enduml

Goal level

Every use case in the diagram is a user goal — what Cockburn calls the sea level: one actor, one sitting, a result the primary actor walks away with. Test each use case with one question:

Is this use case a complete goal that the primary actor would recognize as valuable?

  • Too low (subfunction): a step of a larger goal, often a technical one — "Validate METAR", "Load NOTAM", "Persist Result". No dispatcher sits down to validate a METAR; they want to know whether an airport is suitable. Fold such steps into the user goal they serve ("Determine Airport Suitability"), where they become steps of its main success scenario. Keep a subfunction as its own use case only when several user goals share it, and then draw it with <<include>> from each of them.
  • Too high (summary): a whole area of work that spans many sittings — "Manage Flight Operations". Split it into the user goals it is made of. A use case is a summary, too, when its flow hands the work over to another role, waits for an outside event or a deadline, or runs branches in parallel for different actors — "Process Insurance Claim" with a clerk, an assessor, and a payout after approval. Each role's part is a user goal of its own; the flow that connects them is a business process, modeled in BPMN in docs/processes/ by /business-process once the use cases are specified; its activities are those use cases, and /test-case BP-XXX derives the test cases from it. Do not describe the process inside a use case or attach a process model to it.

A functional requirement that describes a step rather than a goal traces to the user goal use case that contains the step.

Show full SKILL.md (203 more words)Show less

Conventions

  • Each use case has a unique id and a description
  • Use Case ID: UC-{3-digit} (UC-001, UC-002, ...)
  • Each use case should trace to at least one functional requirement
  • Secondary actors (supporting roles and external systems such as a payment or weather service) are drawn as actors too and connected to the use cases they support; they appear as **Secondary Actors:** in the use case specification
  • Add notes sparingly, only where relationships need clarification

Workflow

  1. Read the requirements at docs/requirements.md
  2. Read existing diagram at docs/use_cases.puml (if exists)
  3. Identify actors and use cases from requirements
  4. Check every use case against the question in "Goal level": fold subfunctions into the user goal they serve, split summary goals, and tell the user which use cases you merged or split and why
  5. Create/update the PlantUML use case diagram
  6. Validate the diagram:
    • Each use case is a user goal (see "Goal level"); a subfunction appears only as an <<include>> shared by several use cases
    • Each use case traces to at least one functional requirement in docs/requirements.md
    • All actors are connected to at least one use case
    • Use case IDs follow the UC-{3-digit} convention
    • PlantUML syntax is valid (no missing @enduml, proper arrow syntax)

© AI-Unified-Process, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in aiup-core/skills/use-case-diagram of AI-Unified-Process/marketplace.

Open the folder on GitHubat commit d25bf91

Compare with similar skills

Use Case Diagram next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Use Case Diagram compared with similar skills
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Use Case Diagram this skillAI-Unified-Process/marketplace142—~1.1kAutomated safety check: PassApache-2.0
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JSON Canvasheyitsnoah/claudesidian2.6k18 repos~3.5kAutomated safety check: PassMIT
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Fireworks Tech Graphtisfeng/Easydict15k1 repos~1.4kAutomated safety check: PassMIT
Excalidraw Diagramcoleam00/excalidraw-diagram-skill5k2 repos~6.1kAutomated safety check: PassNone

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Categories

Questions about Use Case Diagram

What does Use Case Diagram do?

Creates or updates PlantUML use case diagrams defining actors, use cases, and their relationships from requirements. Use Case Diagram is an agent skill from AI-Unified-Process/marketplace. Creates or updates PlantUML use case diagrams defining actors, use cases, and their relationships from requirements.

When should I use Use Case Diagram?

Use Case Diagram fits situations like: the user asks to create a use case diagram; draw a UML diagram; map actors to use cases; generate a .puml file.

How do I install Use Case Diagram in Claude Code?

Run `npx skills add AI-Unified-Process/marketplace --skill use-case-diagram -a claude-code`. Or copy the skill folder (aiup-core/skills/use-case-diagram in AI-Unified-Process/marketplace) into .claude/skills/use-case-diagram in your project. Claude Code loads it when a task matches its description.

How do I install Use Case Diagram in Codex?

Run `npx skills add AI-Unified-Process/marketplace --skill use-case-diagram -a codex`. Or copy the skill folder (aiup-core/skills/use-case-diagram in AI-Unified-Process/marketplace) into .agents/skills/use-case-diagram in your project. Codex loads it when a task matches its description.

Can I use Use Case Diagram in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add AI-Unified-Process/marketplace --skill use-case-diagram -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/use-case-diagram, .gemini/skills/use-case-diagram, .github/skills/use-case-diagram and .opencode/skills/use-case-diagram in your project.

What does Use Case Diagram need to run?

SKILL.md names no scripts, command-line tools or credentials: Use Case Diagram is instructions for the agent only.

Does Use Case Diagram access the network?

SKILL.md names 1 domain. As links in the text: unifiedprocess.ai. This is read from the text; nothing was executed.

Is Use Case Diagram safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Use Case Diagram use?

Use Case Diagram is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Use Case Diagram use?

About 1.1k tokens (SKILL.md is roughly 4.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Use Case Diagram?

Skills that share tags, products or a category with Use Case Diagram: Archify Diagrams (tt-a1i/archify, 82k stars), JSON Canvas (heyitsnoah/claudesidian, 2.6k stars), Diagram Design (cathrynlavery/diagram-design, 49k stars) and Fireworks Tech Graph (tisfeng/Easydict, 15k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Use Case Diagram?

AI-Unified-Process (a GitHub organization) maintains it in AI-Unified-Process/marketplace, which has 142 GitHub stars. The repository holds 14 skills in this directory. The repository was last updated on October 5, 2026.

Source: AI-Unified-Process/marketplace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.