D2 vs Structurizr + MCP

D2

A single local command turns text into a diagram in six formats with no account, key or network call, and CI passes on the default branch. The language is at 0.9.0 with no stable release, its company sponsor has shut down, and one maintainer with limited time wrote every commit since July.

Structurizr + MCP

One model can generate several C4 architecture views. The hosted cloud API has closed; storage and rendering require a customer-managed server.

D2

1. Check the exit status of d2, never the output file. The man page says a partial render can be written when an error occurs
2. Run d2 validate file.d2 before rendering, and d2 fmt to normalise the source
3. Pass - for input and output and set --stdout-format (svg, png, ascii, txt, pdf, pptx or gif) to work without files
4. Use --stdout-format ascii when the reader is a text-only model
5. Pass --bundle=false or review image URLs and imports before rendering D2 text from an untrusted source. Release 0.9.0 fetches remote images when bundling

Structurizr + MCP

1. Call validate and then inspect on the DSL before pushing a workspace
2. Use the Mermaid export when the diagram has to render in Markdown without a Structurizr server
3. Export needs a view key. Parse the DSL first to list the views
4. Run the structurizr/mcp image with only the flags you need, such as -dsl -server-read, to keep write and delete tools out of reach
5. The workspace API returns JSON, never images. PNG and SVG come from the separate export command