Personal
PlantUML MCP: UML diagrams from Claude
MCP server that lets Claude generate UML diagrams with PlantUML and show the image in the chat.
Images
Context
Personal tool to create UML diagrams from an AI assistant.
Problem
Asking an AI assistant for a diagram returns PlantUML code that has to be rendered separately.
My role
End-to-end design and implementation.
Solution
Node.js MCP server with three tools: render_diagram (PNG, SVG or ASCII, with the exact line when there is a syntax error), get_diagram_urls (shareable links) and decode_diagram_url (recovers the code from a URL).
Technical decisions
- Rendering on the public PlantUML server: no Java or PlantUML install needed; a self-hosted server with Docker can be used for sensitive information.
- Syntax errors with line numbers, so the assistant can fix the diagram on its own.
Outcome
Diagrams are generated and displayed right in the chat, and the assistant fixes syntax errors on its own.