decode_plantuml
Decode encoded PlantUML string back to PlantUML code
LABSCO SUMMARY
A broken diagram comes back as errors you can act on, not as a broken image.
The auto-fix loop is the reason to pick this over a plain render endpoint: generate_plantuml_diagram reports structured syntax errors, so the agent corrects the source and re-renders without a human reading a rendering log. Rendering happens on whatever PLANTUML_SERVER_URL points at, which decides both where the diagram is drawn and where the returned image URL resolves — worth knowing before diagrams of internal architecture go through a public instance.
What it is
A PlantUML rendering front end, 3 tools: one that validates and renders, and two that convert between PlantUML source and the encoded string a PlantUML URL carries.
What you get
- generate_plantuml_diagram validates before it renders: valid source comes back as an embeddable image URL, invalid source as structured error details rather than a failed image
- The same call optionally writes the diagram to output_path in the format you name, so a document can carry the file rather than a link
- encode_plantuml and decode_plantuml convert in both directions, which is what lets an existing diagram link be read back, edited and re-encoded
Requirements
PLANTUML_SERVER_URL pointing at the PlantUML server that does the rendering, and a writable output_path if the diagram should also be saved locally. MIT licensed.
Setup effort
One command — npx plantuml-mcp-server
USE CASES
01
Getting a diagram into a document
Send the source and take back an embeddable image URL, or write the file to a path in the format the document needs. Invalid syntax comes back as structured errors, so the next attempt is a correction rather than a guess.
02
Editing a diagram you only have the link to
Decode the encoded string out of the existing URL to recover the source, change it, then encode the result back or render it directly.
3 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
encode_plantuml
Encode PlantUML code for URL usage
generate_plantuml_diagram
Generate a PlantUML diagram with automatic syntax validation and error reporting for auto-fix workflows. Returns embeddable image URLs for valid diagrams or structured error details for invalid syntax that can be automatically corrected. Optionally saves the diagram to a local file.
BEFORE YOU INSTALL
What to know first
Tools you get
3 tools when we connected.
Requires
- npx on PATH
- Node.js 18+
- PLANTUML_SERVER_URL in your environment
CONTEXT COST
Light Standing cost
Rated by the size of the 3 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Add the block to your client, or run the command directly.
Server setup
Configuration file
JSON
{
"mcpServers": {
"plantuml": {
"command": "npx",
"args": [
"plantuml-mcp-server"
],
"env": {
"PLANTUML_SERVER_URL": "https://www.plantuml.com/plantuml"
}
}
}
}npx
TERMINAL
npx plantuml-mcp-server
