uml-mcp

Diagram Assistant

The Diagram Assistant is the set of MCP tools, resources, and prompts that help users generate and understand UML and other diagrams. This page describes four example user prompts and how the server satisfies them.

Example prompts and behavior

User prompt	Desired behavior	Tools	Resources
“Show me a Mermaid sequence diagram for an API call”	Return valid Mermaid sequenceDiagram (client → API → backend) and optionally call generate_uml("mermaid", code).	generate_uml	uml://examples (mermaid), uml://mermaid-examples (sequence_api)
“Generate a Gantt chart using Mermaid syntax”	Return valid Mermaid gantt block and optionally call generate_uml("mermaid", code).	generate_uml	uml://mermaid-examples (gantt), uml://templates
“Explain how to draw a BPMN process model”	Return concise guidance (elements, flow, BPMN 2.0.2 alignment) and optionally point to BPMN template/example.	generate_bpmn_diagram, generate_uml	uml://bpmn-guide, uml://templates (bpmn)
“Convert this class diagram into Mermaid code”	Take PlantUML or description and output Mermaid classDiagram; optionally call generate_uml("mermaid", code).	generate_uml	uml://templates, uml://examples

Tools

• generate_uml — Main entry point: pass diagram_type (e.g. class, sequence, mermaid, bpmn) and code to render via Kroki or PlantUML.
• generate_bpmn_diagram — BPMN-specific generator for BPMN XML.
• generate_uml — Single tool; pass diagram_type (class, sequence, mermaid, d2, etc.) and code. Uses Kroki or PlantUML under the hood.

Resources

• uml://types — Available diagram types and backends.
• uml://templates — Starter template code per diagram type (including mermaid, mermaid_gantt-style content via Mermaid examples).
• uml://examples — Full examples per diagram type.
• uml://mermaid-examples — Named Mermaid examples: sequence_api (API call sequence), gantt (Gantt chart).
• uml://bpmn-guide — Short BPMN 2.0.2-oriented guide: core elements (Start/End events, Task, Gateways, Sequence Flow, Lanes), flow rules, and pointer to BPMN template/tools.
• uml://formats — Supported output formats per type.
• uml://server-info — Server name, version, tools, prompts.
• uml://workflow — Recommended workflow: plan first (type, elements, relationships), then call generate_uml.

Prompts

Registered prompts that support the four scenarios above:

• mermaid_sequence_api — Produce a Mermaid sequence diagram for an API call (client, API, auth/DB, request/response, optional alt); then call generate_uml("mermaid", code).
• mermaid_gantt — Produce a Mermaid Gantt chart with title, dateFormat, sections, and tasks; then call generate_uml("mermaid", code).
• bpmn_process_guide — Explain how to draw a BPMN process (elements, flow, BPMN 2.0.2); point to uml://bpmn-guide and generate_bpmn_diagram / generate_uml("bpmn", ...).
• convert_class_to_mermaid — Convert a class diagram (PlantUML or prose) into Mermaid classDiagram and optionally call generate_uml("mermaid", code).

Other diagram prompts (e.g. class_diagram, sequence_diagram, uml_diagram_with_thinking) remain available for general UML generation.

Supported diagram types

The server supports (among others): class, sequence, activity, usecase, state, component, deployment, object, mermaid, d2, graphviz, erd, blockdiag, packetdiag, bpmn, c4plantuml. See uml://types for the full list and descriptions.

Reference

• Kroki cheatsheet and docs for syntax and supported diagram types.
• BPMN 2.0.2 (OMG) for BPMN terminology and element set.
• Skill: .skill/skills/uml-diagramming/SKILL.md and references/DIAGRAM-TYPES.md for type mappings and examples.

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