| 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
- Read
uml://types / uml://capabilities when the type is ambiguous.
- Use
uml://templates, uml://examples, or uml://recipes for starters.
- 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.
