tidy3d-mcp 0.16.3

Local stdio FastMCP server for Tidy3D

Tidy3D MCP

A small local MCP server that lets your IDE or AI assistant validate Tidy3D simulations and control the in-editor 3D viewer (rotate, toggle structures, take screenshots).

What You Need

• A Tidy3D API key (from your Tidy3D account).
• The server resolves the key in this order: manual CLI flag --api-key (for tidy3d-mcp ... runs), environment variable SIMCLOUD_APIKEY, config files under environment variable TIDY3D_BASE_DIR (when set), then ~/.config/tidy3d/config.toml ([web].apikey) and finally ~/.tidy3d/config (legacy). It fails fast if none are present.
• The Tidy3D extension for your IDE:
  • Visual Studio Marketplace: https://marketplace.visualstudio.com/items?itemName=Flexcompute.tidy3d
  • Open VSX Registry: https://open-vsx.org/extension/Flexcompute/tidy3d

Typical Use

• In VS Code or Cursor, install the Tidy3D extension. It automatically registers and runs this MCP server. When prompted, enter your API key. You can then ask your assistant to "validate my Tidy3D simulation" or "capture a screenshot," and the viewer responds inside the editor.

Manual Use (Advanced Hosts)

• If your MCP host expects an stdio command, run:

tidy3d-mcp --api-key YOUR_TIDY3D_API_KEY

• Add --enable-viewer to expose viewer controls (rotate, visibility, capture).

Available Tools

• validate_simulation(file?, symbol?, index?, viewer_id?) — Validate or refresh a simulation; returns status, warnings, and a reusable viewer_id.
• rotate_viewer(viewer_id, direction) — Align to TOP|BOTTOM|LEFT|RIGHT|FRONT|BACK.
• show_structures(viewer_id, visibility[]) — Show/hide structures by boolean flags.
• capture(viewer_id) — Return a screenshot image.

Troubleshooting

• Assistant can’t control the viewer: install/enable the Tidy3D extension and verify your API key.
• Viewer tools missing when running manually: include --enable-viewer.
• Still stuck: re-run the extension’s setup command in your IDE and confirm network access.