Which integrations are available for this server?

Supports generating Excalidraw diagrams as one of the specialized diagram types available through the server. Enables generating Mermaid diagrams from textual definitions and rendering them to SVG, PNG, PDF, JPEG, or base64 outputs. Allows generating UML diagrams, including class, sequence, activity, use case, state, component, deployment, and object diagrams.

How do I use UML-MCP?

1. Click on "Deploy Server". 2. Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state. 3. In the chat, type @ followed by the MCP server name and your instructions, e.g., "@UML-MCP Generate a UML class diagram for a library management system" That's it! The server will respond to your query, and you can continue using it as needed. Here is a step-by-step guide with screenshots.

UML-MCP

by Delight-L

Overview Schema Source Related Servers Discussions Admin

Python

Hybrid

UML-MCP: Diagram Generation via MCP

Generate UML and other diagrams through the Model Context Protocol.

At a glance

Topic	What you get
Diagrams	30+ types: UML (Class, Sequence, Activity, Use Case, State, Component, Deployment, Object), Mermaid, D2, Graphviz, TikZ, ERD, BlockDiag, BPMN, C4, and more via Kroki
MCP tools	`generate_uml`, `validate_uml`, `list_diagram_types`, `generate_uml_batch`
Outputs	SVG, PNG, PDF, JPEG, base64 (availability varies by diagram type)
Pipeline	Kroki first, then PlantUML or Mermaid.ink
Deployment	Local stdio, local HTTP, Docker, Vercel, Smithery

Source	URL
Live MCP (HTTP)	https://uml-mcp.vercel.app/mcp
Smithery catalog	Add via Smithery

Quick Start

Choose your mode

Remote (recommended): Fast setup over HTTP MCP with Vercel serverless runtime
Local: stdio process for file output and local debugging

Remote quick start (Vercel HTTP MCP)

Configuration for the public Vercel deployment:

"uml-mcp": {
  "transport": "http",
  "url": "https://uml-mcp.vercel.app/mcp"
}

Local quick start (stdio MCP)

git clone https://github.com/antoinebou12/uml-mcp.git && cd uml-mcp
uv sync
uv run python server.py

Example client configs:

config/cursor_config.json
config/claude_desktop_config.json
config/README.md for exact config file locations
Claude Code: install the bundled plugin from the repo marketplace (see below) or read docs/integrations/claude_code.md

Claude Code plugin

Adds the hosted HTTP MCP server plus a diagram skill (no settings.json paste). In Claude Code:

/plugin marketplace add https://github.com/antoinebou12/uml-mcp
/plugin install uml-mcp@uml-mcp-plugins

Use a local path instead of the GitHub URL if you already cloned this repo. Custom endpoints and validation: docs/integrations/claude_code.md.

Related MCP server: Draw.io MCP Server

Remote vs Local

Transport: Remote uses HTTP MCP, local uses stdio by default
Runtime: Remote runs on Vercel, local runs in your Python environment
File writes: Remote is read-only (no output_dir), local supports output_dir
Returned data: Both return URL + base64; local can also save files
Environment variables: Remote is managed server-side; local reads your env config

MCP clients must call /mcp, not the site root.

Supported Diagram Types

Category	Examples
UML (PlantUML)	Class, Sequence, Activity, Use Case, State, Component, Deployment, Object
General	Mermaid, D2, Graphviz, ERD, BlockDiag, BPMN, C4
Specialized	TikZ, Excalidraw, Nomnoml, Pikchr, Structurizr, SVGBob, WaveDrom, WireViz, …

Full list with supported formats: run python server.py --list-tools or query uml://types and uml://formats.

MCP Tools and Resources

Tools

Tool	Purpose
`generate_uml`	Render a diagram; omit `output_dir` for URL/base64 only
`validate_uml`	Structural validation before render; `strict` enables extra Mermaid/D2 checks
`list_diagram_types`	Same metadata as `uml://types` when resources are awkward
`generate_uml_batch`	Multiple diagrams in one call (cap: `MCP_BATCH_MAX_ITEMS`)

Resources (`uml://`)

Resource	Description
`uml://types`	Diagram types, backends, supported formats per type
`uml://templates`	Starter templates per type; see BPMN 2.0.2 guide for element and flow reference (docs)
`uml://examples`	Example diagrams per type; Mermaid documents named samples (sequence API, Gantt) alongside `uml://examples` (key `mermaid`)
`uml://formats`	Output formats per type
`uml://capabilities`	Type → backend → formats matrix used for validation
`uml://server-info`	Server name, version, tools, prompts, Kroki/PlantUML URLs
`uml://workflow`	Recommended plan-then-generate workflow

Deployment

Vercel

This repo includes vercel.json for serverless deployment.

Connect the repo to Vercel
Use https://<project>.vercel.app/mcp
Keep /mcp in all MCP client URLs

Smithery

Open smithery.ai/new, choose URL
Enter https://<project>.vercel.app/mcp
Configure display name, description, and homepage

Detailed guide: docs/integrations/vercel_smithery.md

Docker

Default image serves FastAPI on port 8000 with MCP HTTP at http://127.0.0.1:8000/mcp.

# Full local stack (local Kroki + mermaid + blockdiag)
docker compose up -d

# API + MCP only (public Kroki)
docker build -t uml-mcp . && docker run -p 8000:8000 uml-mcp

# stdio MCP subprocess mode
docker run -i uml-mcp python server.py --transport stdio

Configuration (Local runtime)

These variables apply to local/self-hosted runs. Remote Vercel endpoint settings are managed server-side.

Variable	Description	Default
`KROKI_SERVER`	Kroki server URL	`https://kroki.io`
`PLANTUML_SERVER`	PlantUML server URL	`http://plantuml-server:8080`
`MCP_OUTPUT_DIR`	Diagram output directory	`./output`
`MCP_READ_ONLY`	Disable file writes	`false`
`MCP_MAX_CODE_LENGTH`	Max diagram code length	`500000`
`MCP_BATCH_MAX_ITEMS`	Max items per `generate_uml_batch`	`20`
`MCP_RATE_LIMIT_PER_MINUTE`	HTTP rate limit per IP for diagram/MCP routes (`0` = off)	`0`
`USE_LOCAL_KROKI`	Use local Kroki instance	`false`
`USE_LOCAL_PLANTUML`	Use local PlantUML instance	`false`

Full options: docs/configuration.md

Architecture

Typical flow when a user asks an MCP-enabled assistant for a diagram: the assistant calls generate_uml, the server renders via Kroki, then returns URLs and optional base64 to the assistant for the user.

server.py              -- MCP entry point (stdio/HTTP)
app.py                 -- FastAPI REST API + MCP HTTP at /mcp
api/app.py             -- legacy re-export of root app (Vercel FastAPI preset uses root app.py)
mcp_core/
  core/                -- config, server, CLI, utilities, diagram pipeline
  tools/               -- generate_uml, validate_uml
  prompts/             -- diagram generation prompts
  resources/           -- uml:// resource handlers
tools/kroki/           -- Kroki, PlantUML, Mermaid, D2 clients

Development

# Install dev dependencies
uv sync --all-groups

# Run tests
uv run pytest tests/ -v

# Lint
uv run ruff check . && uv run ruff format --check .

# Local CI
make ci

Documentation

Built with MkDocs + Material:

Online: antoinebou12.github.io/uml-mcp
Local: uv run mkdocs serve then open http://127.0.0.1:8000

Contributing

License

MIT

Acknowledgements

PlantUML | Kroki | Mermaid | D2

Star History

Available Tools

4 tools

generate_umlB

Idempotent

Generate any UML or diagram by type (class, sequence, mermaid, d2, etc.)

Inputs: code (required), diagram_type (required), scale, theme, +2 more. Returns: object

generate_uml_batchA

Idempotent

Generate multiple diagrams in one call. Each item is like generate_uml (diagram_type, code, output_format?, theme?, scale?). Optional shared output_dir for all items. Returns a list of per-index results or errors.

Inputs: items (required), output_dir. Returns: object

list_diagram_typesA

Read-onlyIdempotent

List supported diagram types with Kroki backend, description, and formats (same data as uml://types resource). Use when the client cannot read resources.

Inputs: no named parameters. Returns: object

validate_umlA

Read-onlyIdempotent

Validate diagram type, format, code length, and basic syntax locally before render (no Kroki call). Returns errors and suggestions.

Inputs: code (required), diagram_type (required), strict, output_format. Returns: object

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

Loading tool schema changelog…

Deploy Server

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TDQS

A4.1/5.0

Scored 2026-09-14 14:20 across 4 tools

Disambiguation5/5

Each tool has a clearly distinct role: listing available types, validating before render, generating a single diagram, and batch-generating multiple diagrams. The single vs. batch generation pair is unambiguous given the explicit descriptions.

Naming Consistency5/5

All four tools follow a consistent verb_noun snake_case pattern (list_diagram_types, generate_uml, generate_uml_batch, validate_uml). No mixing of conventions.

Tool Count5/5

Four tools is well-scoped for a diagram rendering service, covering discovery, validation, single generation, and batch generation without redundancy. Each tool clearly earns its place.

Completeness4/5

The surface covers the full diagram workflow: discover types, validate, generate, and batch generate. Minor gap in that there is no explicit info/help tool, though list_diagram_types largely covers discovery.

Maintenance

ActivitySlowing

ResponsivenessNo recent community issues

Resources

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