uml-diagrams

name	uml-diagrams
description	Create and validate diagrams with the uml-mcp MCP server (generate_uml, validate_uml, list_diagram_types, generate_uml_batch). Use for UML, Mermaid, D2, Graphviz, Kroki URLs, or diagram_type questions.

Maintainers: Canonical long-form copy also lives in .skill/skills/uml-mcp-diagrams/SKILL.md. Keep tool tables and output_dir wording aligned with the Smithery bundle uml-skill.

UML-MCP in Claude Code

Goal

Produce valid diagram_type and DSL code, call generate_uml, and give the user the url (and playground when present). Prefer URL-first output: omit output_dir / use null unless the user wants files on disk (local stdio only).

Do

• If diagram_type is unclear, use list_diagram_types or read uml://types / uml://formats before generate_uml.
• Match diagram_type to the language of code (e.g. Mermaid body → mermaid; @startuml → plantuml or the specific Kroki PlantUML subtype when applicable).
• Use validate_uml before heavy retry loops or on pasted diagram source.
• Return the url plus a short copy of code so the user can edit and regenerate.

Do not

• Invent diagram_type or output_format; confirm from uml://types / uml://formats or list_diagram_types.
• Put prose inside code—only valid diagram DSL.
• Set output_dir unless the user asked for saved files (not applicable to the default HTTP deployment).

Before generating

1. Read uml://types / uml://capabilities when the type is ambiguous.
2. Use uml://templates, uml://examples, or uml://recipes for starters.
3. Optional: validate_uml with strict: true for stricter Mermaid/D2 checks.

Tools and resources

• Tools: generate_uml, validate_uml, list_diagram_types, generate_uml_batch
• Resources: uml://types, uml://formats, uml://templates, uml://examples, uml://capabilities, uml://recipes, uml://server-info, uml://workflow, plus URIs from resources/list

Prompts (when exposed): uml_diagram, uml_diagram_with_thinking, class_diagram, sequence_diagram, activity_diagram, usecase_diagram, mermaid_sequence_api, mermaid_gantt, bpmn_process_guide, c4_model, wireviz_harness, bpmn_executable_process, convert_class_to_mermaid, algorithm_explainer, paper_concept_diagram.

generate_uml inputs

Field	Notes
diagram_type	Required; must match server-supported keys.
code	Required; DSL only.
output_dir	Omit for HTTP MCP (URL + base64 in response).
output_format	Often svg; check uml://formats for the type.
theme	PlantUML types only.
scale	SVG only.

After generation

Highlight url, then playground if present, then local_path only when output_dir was used. On error, fix DSL or types and retry or run validate_uml.

Intent → type hints

Intent	Typical diagram_type
Classes / associations	class or Mermaid classDiagram
Lifelines / messages	sequence or Mermaid sequence
Flow / BPMN	activity, bpmn, or Mermaid flowchart
Quick charts	mermaid
Declarative layout	d2

When several fit, prefer what the user named; otherwise prefer the clearest match from uml://types.