Migrating from design-system-mcp

@dgesteves/design-system-mcp is now onsystem. Version 0.4.0 is the first release under the new name; the old package stays at 0.3.3 and gets no new releases. The rules, their ids and defaults, the CLI flags and the output formats are the same, and the files you already have keep working until you rename them: each old name is still read, with a notice that says what to rename.

What changed

The package and CI

Swap the dev dependency, and use the new command in scripts and CI:

npm uninstall @dgesteves/design-system-mcpnpm install --save-dev onsystem

- run: npx onsystem check . --format github --require-design-system

With pnpm, Yarn or Bun, use pnpm remove and pnpm add -D, yarn remove and yarn add -D, or bun remove and bun add -d.

Config and baseline files

Rename them, and point $schema at the new URL:

git mv design-system-mcp.config.json onsystem.config.jsongit mv design-system-mcp.baseline.json onsystem.baseline.json

Until you do, check, inspect and the server read the old names and print a notice once per run (a warning annotation with --format github). check --update-baseline updates an old-name baseline where it is rather than writing a second file. When both names exist, the new one is read and the notice says to delete the old one.

A .ts, .mts, .js or .mjs config that imports defineConfig from @dgesteves/design-system-mcp needs the import changed to onsystem; if the old package is no longer installed, the error says so.

The Claude Code plugin

The plugin moved from design-system to onsystem in the same dgesteves marketplace. Remove the old one, refresh the marketplace, and install the new one:

/plugin uninstall design-system@dgesteves/plugin marketplace update dgesteves/plugin install onsystem@dgesteves

New installs add the marketplace with /plugin marketplace add dgesteves/onsystem; a marketplace added from the old repository name keeps working, since GitHub redirects it. The plugin now runs an exact version of the package (onsystem@0.4.0 for 0.4.0) instead of a range, and moves to each new release with the plugin.

Other MCP clients

Rename the server's key and the package in its entry. For example, in .cursor/mcp.json:

{  "mcpServers": {    "onsystem": {      "command": "npx",      "args": ["-y", "onsystem", "--root", "${workspaceFolder}"]    }  }}

The key is part of each tool's name in most clients, so mcp__design-system__check_ui becomes mcp__onsystem__check_ui. Update any permission allowlists that name the old tools, and any line in CLAUDE.md, AGENTS.md or .cursor/rules that mentions the design-system tools. The setup guide has the entry for every client.

Clean up

The old cache folder is no longer used and can be deleted:

rm -rf node_modules/.cache/design-system-mcp