MCP

An alternative to the Excalidraw MCP server.

Same format, no lock-in, and a solver does the arranging.

Download for macOS
v0.1.33 · .dmg · Apple Silicon & Intel
Signed & notarized by Apple · opens without a Gatekeeper warning
sha256 698955a0187bc039f4c74f5d05a9f10fbb27376a45788a0a241d1326b73873c7
Download for Windows instead
$curl -fsSL https://lucidtrain.com/install.sh | sh

Lucid Train's MCP server produces standard Excalidraw scenes, so output opens in Excalidraw and any compatible client exactly as an Excalidraw MCP server's would. The difference is that positions come from the ELK constraint solver rather than from the language model, and cards carry real bundled service logos. Same file format, no lock-in, no manual arrangement afterwards.

The format is identical

Diagrams are persisted as standard .excalidraw scenes, so anything produced here opens in Excalidraw. That was deliberate: a diagram locked into a format one application reads is a diagram you eventually lose. So this is not a migration decision, it is a decision about who arranges the elements.

Solver-computed positions

An Excalidraw MCP server that exposes element creation puts the model in charge of coordinates, with the usual result on anything past a few nodes. emit_diagram takes a semantic graph with no coordinates and ELK computes the arrangement, including orthogonal edge routing and tier bands that make dependency direction readable at a glance.

Icons that render offline

Around forty-five brand logos plus generic architecture glyphs ship with the tool, inlined into the scene as image elements. Nothing is fetched, so a diagram renders identically on an isolated network or a plane, which is a failure mode people usually discover at the worst moment.

Transport

Connections are stdio: the server runs as a local child process with piped stdin and stdout. Remote HTTP and SSE servers appear in the Connectors tab's registry search but cannot be connected, and that is a real limit rather than a configuration step you are missing. A remote server needs a local stdio bridge in front of it.

Sketching is still Excalidraw's job

For the first fifteen minutes of a design conversation, drawing by hand in Excalidraw is better and free, and the hand-drawn style usefully signals that a diagram is provisional. This is for when the diagram needs to match a real system and stay matching it.

FAQ

Questions

Do the diagrams open in Excalidraw?

Yes, they are standard Excalidraw scenes. Nothing is proprietary about the output format.

Why use this instead of an Excalidraw MCP server directly?

Because positions come from a constraint solver rather than the model, cards carry real service logos, and tier bands are computed rather than drawn. The file you end up with is the same kind of file.

Can I edit the result by hand afterwards?

Yes, in the desktop app or any Excalidraw client. Editing the graph and re-solving keeps alignment; editing the scene by hand is free-form from that point on.

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