Agent skill

Plantuml Syntax

by tractorjuice in tractorjuice/arc-kit

PlantUML syntax reference, C4-PlantUML first, for writing or fixing a diagram in an artefact: sequence, class, activity, state, ER, component, deployment and use-case diagrams, skinparams and…

Custom licenceAuto-check passedDevelopment

Install Plantuml Syntax

skills CLI
$ npx skills add tractorjuice/arc-kit --skill plantuml-syntax -a claude-code

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

GitHub CLI
$ gh skill install tractorjuice/arc-kit plantuml-syntax --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/tractorjuice/arc-kit.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/arckit-claude/skills/plantuml-syntax .claude/skills/plantuml-syntax && 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
plantuml-syntax
GitHub stars
2.3k
Token cost
~1.3k tokens
SKILL.md length
483 words
Files
12 (incl. references)
Skills in repo
9
Repo updated
First seen
Licence
Custom licence

At a glance

PlantUML syntax reference, C4-PlantUML first, for writing or fixing a diagram in an artefact: sequence, class, activity, state, ER, component, deployment and use-case diagrams, skinparams and…

  • Tasks that involve Diagrams
  • SKILL.md covers Supported Diagram Types, Styling & Errors, C4-PlantUML (Primary Use Case) and Common Syntax Gotchas, plus 1 more section
  • Reaches raw.githubusercontent.com

What it does

Plantuml Syntax is an agent skill from tractorjuice/arc-kit. PlantUML syntax reference, C4-PlantUML first, for writing or fixing a diagram in an artefact: sequence, class, activity, state, ER, component, deployment and use-case diagrams, skinparams and themes, C4 layout conflicts and rendering errors. Not needed for Mermaid (mermaid-syntax), or when the request is for a governed diagram artefact with document control, which /arckit:diagram produces.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. The skill folder holds 12 other files, including reference files (for example `references/activity-diagrams.md`, `references/c4-plantuml.md` and `references/class-diagrams.md`).

It sits in Development, covering Diagrams. It works with Mermaid and Model Context Protocol. The repository describes itself as: The Enterprise Architecture Governance Harness — strategy, architecture, delivery, and assurance using AI coding assistants.

When your agent uses it

  • Tasks that involve Diagrams

Example prompts

  • “/plantuml-syntax”

Requirements

  • Pre-approved tools (allowed-tools): Read(/${CLAUDE_PLUGIN_ROOT}/**)

What it can do on your machine

Read from SKILL.md and the folder at commit 6d5ad01. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read(/${CLAUDE_PLUGIN_ROOT}/**)

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

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

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • raw.githubusercontent.com

    Also links to:

    • github.com

    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

Plantuml Syntax loads about 1.3k tokens when it runs, and up to ~17k if it reads all its reference files. Until then it costs about 102 tokens; SKILL.md has 483 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~102
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~17k

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

Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 483 words (~1,331 tokens).

“A comprehensive reference for PlantUML diagram types with a focus on C4-PlantUML for architecture diagrams. This skill provides syntax documentation adapted from the SpillwaveSolutions/plantuml project, supplemented with ArcKit-specific C4 layout conflict rules and best practices.”

— opening of SKILL.md by tractorjuice, Custom licence
name
plantuml-syntax
allowed-tools
Read(/${CLAUDE_PLUGIN_ROOT}/**)
paths
**/*.puml, **/*.plantuml, **/ARC-*-DIAG-*.md

Read the full SKILL.md on GitHub

Files

SKILL.md and 11 other files (references) in plugins/arckit-claude/skills/plantuml-syntax of tractorjuice/arc-kit.

  • SKILL.md
  • references/activity-diagrams.md
  • references/c4-plantuml.md
  • references/class-diagrams.md
  • references/common-syntax-errors.md
  • references/component-diagrams.md
  • references/deployment-diagrams.md
  • references/er-diagrams.md
  • references/sequence-diagrams.md
  • references/state-diagrams.md
  • references/styling-guide.md
  • references/use-case-diagrams.md

Open the folder on GitHubat commit 6d5ad01

Compare with similar skills

Plantuml Syntax 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.

Plantuml Syntax compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Plantuml Syntax this skilltractorjuice/arc-kit2.3k—~1.3kAutomated safety check: PassCustom licence
Excalidraw Skillyctimlin/mcp_excalidraw2.5k—~4.6kAutomated safety check: PassMIT
GitDiagram Repository Overviewahmedkhaleel2004/gitdiagram18k—~427Automated safety check: PassMIT
Drawiobahayonghang/drawio-skills287—~4.1kAutomated safety check: NotesMIT
Mermaid Diagramsveelenga/claude-mermaid216—~1.3kAutomated safety check: PassMIT
Excalidraw Canvas Toolkitlingzhi227/agent-research-skills390—~3.8kAutomated safety check: PassNone

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Categories

Questions about Plantuml Syntax

What does Plantuml Syntax do?

PlantUML syntax reference, C4-PlantUML first, for writing or fixing a diagram in an artefact: sequence, class, activity, state, ER, component, deployment and use-case diagrams, skinparams and…. Plantuml Syntax is an agent skill from tractorjuice/arc-kit. PlantUML syntax reference, C4-PlantUML first, for writing or fixing a diagram in an artefact: sequence, class, activity, state, ER, component, deployment and use-case diagrams, skinparams and themes, C4 layout conflicts and rendering errors.

When should I use Plantuml Syntax?

Plantuml Syntax fits situations like: tasks that involve Diagrams.

How do I install Plantuml Syntax in Claude Code?

Run `npx skills add tractorjuice/arc-kit --skill plantuml-syntax -a claude-code`. Or copy the skill folder (plugins/arckit-claude/skills/plantuml-syntax in tractorjuice/arc-kit) into .claude/skills/plantuml-syntax in your project. Claude Code loads it when a task matches its description.

How do I install Plantuml Syntax in Codex?

Run `npx skills add tractorjuice/arc-kit --skill plantuml-syntax -a codex`. Or copy the skill folder (plugins/arckit-claude/skills/plantuml-syntax in tractorjuice/arc-kit) into .agents/skills/plantuml-syntax in your project. Codex loads it when a task matches its description.

Can I use Plantuml Syntax 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 tractorjuice/arc-kit --skill plantuml-syntax -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/plantuml-syntax, .gemini/skills/plantuml-syntax, .github/skills/plantuml-syntax and .opencode/skills/plantuml-syntax in your project.

What does Plantuml Syntax need to run?

SKILL.md names no scripts, command-line tools or credentials: Plantuml Syntax is instructions for the agent only. Its frontmatter pre-approves these tools: Read(/${CLAUDE_PLUGIN_ROOT}/**).

Does Plantuml Syntax access the network?

SKILL.md names 2 domains. In commands or code: raw.githubusercontent.com; the agent is likely to contact it when it follows the instructions. As links in the text: github.com. This is read from the text; nothing was executed.

Is Plantuml Syntax 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 Plantuml Syntax use?

Plantuml Syntax has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.

How many tokens does Plantuml Syntax use?

About 1.3k tokens (SKILL.md is roughly 5.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 15k tokens, read only when the agent opens those files.

What are the alternatives to Plantuml Syntax?

Skills that share tags, products or a category with Plantuml Syntax: Excalidraw Skill (yctimlin/mcp_excalidraw, 2.5k stars), GitDiagram Repository Overview (ahmedkhaleel2004/gitdiagram, 18k stars), Drawio (bahayonghang/drawio-skills, 287 stars) and Mermaid Diagrams (veelenga/claude-mermaid, 216 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Plantuml Syntax?

tractorjuice (a GitHub user) maintains it in tractorjuice/arc-kit, which has 2,253 GitHub stars. The repository holds 9 skills in this directory. The repository was last updated on October 8, 2026.

Source: tractorjuice/arc-kit on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.