uml-mcp

Usage Examples

This page provides examples of using UML-MCP with different environments and diagram types.

Basic Usage with Cursor

When using Cursor with UML-MCP configured, you can generate diagrams by asking the AI assistant:

Generate a class diagram for a banking system with Account, Customer, and Transaction classes.

The AI will use UML-MCP’s tools to generate and display the diagram directly in your conversation.

AI Assistant Prompts

Here are some example prompts for generating diagrams:

Class Diagram

Create a class diagram showing the relationships between the following classes:
- Person (name, age, email)
- Student (studentId, enrollCourse())
- Teacher (employeeId, teachCourse())
- Course (courseId, title, description)

Students can enroll in multiple courses, and each course can have one teacher.

Sequence Diagram

Generate a sequence diagram for an e-commerce checkout process involving:
- Customer
- ShoppingCart
- OrderSystem
- PaymentProcessor
- InventorySystem

Component Diagram

Create a component diagram for a microservices architecture with:
- API Gateway
- User Service
- Product Service
- Order Service
- Payment Service
- Notification Service

Diagram assistant (example prompts)

The server supports a diagram-assistant workflow for common requests. Use these example prompts with your MCP client (e.g. Cursor, Claude Desktop); the assistant will use the right tools, resources, and prompts.

User prompt	What happens	Tools / resources
Show me a Mermaid sequence diagram for an API call	Returns a Mermaid sequenceDiagram (client → API → backend) and can render it.	Prompt: mermaid_sequence_api. Resource: uml://mermaid-examples (key sequence_api). Tool: generate_uml("mermaid", code).
Generate a Gantt chart using Mermaid syntax	Returns a Mermaid gantt block and can render it.	Prompt: mermaid_gantt. Resource: uml://mermaid-examples (key gantt). Tool: generate_uml("mermaid", code).
Explain how to draw a BPMN process model	Explains BPMN 2.0.2 elements (events, tasks, gateways, flow, lanes) and how to generate BPMN.	Prompt: bpmn_process_guide. Resource: uml://bpmn-guide. Tool: generate_bpmn_diagram or generate_uml("bpmn", code).
Convert this class diagram into Mermaid code	Converts PlantUML or prose class diagram to Mermaid classDiagram and can render it.	Prompt: convert_class_to_mermaid. Tool: generate_uml("mermaid", code).

Resources

• uml://types — All supported diagram types (all Kroki backends: plantuml, mermaid, d2, graphviz, blockdiag, seqdiag, bpmn, vega, vegalite, wavedrom, wireviz, etc.).
• uml://templates — Starter templates per diagram type.
• uml://examples — Full examples per diagram type.
• uml://mermaid-examples — Mermaid API sequence and Gantt examples.
• uml://bpmn-guide — BPMN 2.0.2 process modeling guide.

Public references (syntax and specs)

• Kroki — Supported diagram types and rendering.
• Mermaid — Mermaid syntax (sequence, gantt, classDiagram, etc.).
• OMG BPMN 2.0.2 — BPMN specification.

Using MCP Tools Directly

If you’re building an application that uses UML-MCP, you can call the tools directly:

Python Example

import json
import subprocess

def generate_class_diagram(code):
    # Start the MCP server process
    process = subprocess.Popen(
        ["python", "server.py"],
        stdin=subprocess.PIPE,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        text=True
    )

    # Prepare MCP request (use generate_uml with diagram_type for any diagram)
    request = {
        "type": "tool",
        "name": "generate_uml",
        "args": {
            "diagram_type": "class",
            "code": code,
            "output_dir": "./output"
        }
    }

    # Send request to MCP server
    process.stdin.write(json.dumps(request) + "\n")
    process.stdin.flush()

    # Read response
    response = json.loads(process.stdout.readline())

    # Close process
    process.terminate()

    return json.loads(response["result"])

# Example usage (PlantUML class diagram)
diagram = generate_class_diagram("""
@startuml
class User {
  -name: String
  -email: String
  +register(): void
  +login(): boolean
}
@enduml
""")

print(f"Diagram URL: {diagram['url']}")
print(f"Local file: {diagram['local_path']}")

Integration Examples

Web Application

async function generateDiagram(diagramType, code) {
  const response = await fetch('/api/diagram', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      type: diagramType,
      code: code
    }),
  });

  const result = await response.json();
  document.getElementById('diagram').src = result.url;
  document.getElementById('playground-link').href = result.playground;
}

Command Line

echo '{
  "type": "tool",
  "name": "generate_uml",
  "args": {
    "diagram_type": "sequence",
    "code": "@startuml\nAlice -> Bob: Hello\nBob --> Alice: Hi\n@enduml",
    "output_dir": "./diagrams"
  }
}' | python server.py

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