@sub-design/mcp

A local MCP server for @sub-design/ui and @sub-design/tokens — four tools, no hosting, no auth. Answers come from whatever version of those packages is actually installed in the project the server is invoked from, not a snapshot bundled into this package.

Why local, not hosted

The obvious alternative — one hosted server answering for "the current version" — has no good answer to "current according to which consumer." NOKL and Enterprise pin @sub-design/ui independently and are rarely on the same version at the same time; a hosted snapshot would be right for one and stale for the other, silently. Reading from node_modules at the caller's cwd sidesteps the question rather than solving it: there is no shared "current," so nothing tries to be one.

Installing

Add to a project's MCP client config (e.g. .mcp.json):

{
  "mcpServers": {
    "sub-design": {
      "command": "npx",
      "args": ["-y", "@sub-design/mcp"]
    }
  }
}

Requires @sub-design/ui and/or @sub-design/tokens to be installed in the project the client runs from — the server reads their metadata.json / dtcg/*.json via normal Node module resolution starting at process.cwd().

Tools

• list_components — every component's name, source file, and variant prop names. Cheap; call this before searching or fetching one.
• get_component(name) — full detail for one component: props, variants' actual options, the tokens its family depends on, sibling parts (e.g. CardHeader/CardContent for Card), and the promotion rationale.
• search_components(query) — find components by name, variant value, token, or rationale text.
• search_tokens(query) — find design tokens by name or description in the DTCG export. Values shown for theme-layer tokens are GoodSync light specifically; check the actual theme file for anything brand-sensitive.

What this deliberately doesn't do

No component-usage validation, no code generation, no Figma sync. Those are real capabilities other design-system MCP servers have, and real future work here too — this is the lookup layer they'd be built on, not a replacement for building them.