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MCP SERVER

Diagrams MCP Server

by ByteOverDev ↗

Cloud architecture diagrams, flowcharts and UML rendered to images, with node discovery so the model picks real service classes instead of guessing.

Diagrams & Charts
Summary
The discovery tools are what stop the diagram being wrong.

Cloud diagram libraries fail with models for a specific reason — the node classes and import paths are long and easy to hallucinate — and this server solves that by making the catalogue searchable before the render call. Having a hosted endpoint that needs no Graphviz, Java or Mermaid CLI on your machine removes the other usual obstacle.

What it is

A diagram server backed by three rendering engines — mingrammer/diagrams for cloud architecture, Mermaid for flowcharts and sequence diagrams, and PlantUML for UML. The discovery tools are what make it work with a model: rather than hoping the right import path is remembered, the model can list providers, browse services and search nodes by keyword before it writes any diagram code.

What you get
  • Render: `render_diagram` runs a mingrammer/diagrams Python script in a sandboxed subprocess and returns a PNG, `render_mermaid` renders a Mermaid definition, `render_plantuml` renders a PlantUML one
  • Discover before you draw: `list_providers`, `list_services`, `list_nodes` with import paths, and `search_nodes` for keyword search across every provider
  • Cross-cloud equivalence: `find_equivalent` maps a node to its counterpart on another provider, and `list_categories` lists all 30 infrastructure role categories with their mapped nodes
  • Reference material as MCP resources — `diagrams://reference/diagram`, `diagrams://reference/edge`, `diagrams://reference/cluster`, `diagrams://reference/mermaid` and `diagrams://reference/plantuml`
Requirements

Nothing — no account, no key. The simplest path is the hosted endpoint at `https://diagrams-mcp-production.up.railway.app/mcp`, which has every render dependency pre-installed and needs no local setup. Running it yourself: the package is `diagrams-mcp-server` (0.3.0 in pyproject), launched with `uvx diagrams-mcp-server` over stdio, and local rendering needs Graphviz for `render_diagram`, the Mermaid CLI for `render_mermaid`, and Java plus plantuml.jar for `render_plantuml`. A split mode exists for hosting, where `DIAGRAMS_RENDERER_MODE=remote` and `DIAGRAMS_RENDERER_URL` point a slim facade at a separate renderer service.

Setup effort

One command — claude mcp add diagrams-mcp https://diagrams-mcp-production.up.railway.app/mcp