Versioned MCP instances ?

[Powerplex]

Summary

Hey 🙂 I have a question regarding MCP.

Let's say I have a design system, single package published on NPM.

I have 2 consumers, each using a different version of my design system, let's say:
consumer A uses @my-ds@1.3.0
consumer C uses the newly released @my-ds@2.0.0

My issue is I have a single chromatic instance of my storybook matching my main branch (let's say latest npm version). It means that for an AI agent used by a developer from consumer A, the MCP will have context that is NOT supposed to be available to it, but only to consumer B (using the latest version).

How do we manage that ?

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[barry166]

I would treat the MCP endpoint as versioned with the Storybook build, not as a single global service. The addon exposes the currently running Storybook's component data at that instance's MCP path (/mcp by default, or a custom pathname), so an agent connected to your main-branch Storybook will see main-branch stories/docs.

For your example, publish or run separate Storybooks for @my-ds@1.3.0 and @my-ds@2.0.0, then give each consumer an MCP config pointing at the matching URL:

{
  "mcpServers": {
    "my-ds-storybook": {
      "type": "http",
      "url": "https://storybook-for-1-3-0.example.com/mcp"
    }
  }
}

If you use Chromatic, that means separate version/release Storybook URLs rather than one main-branch URL. A custom endpoint path can rename /mcp, but it does not solve versioning by itself; the isolation boundary should be the Storybook deployment/URL.

[stefisha]

I’d version the MCP endpoint alongside the package and build Storybook from the same release tag.

For example:

https://storybook.example.com/1.3.0/mcp
https://storybook.example.com/2.0.0/mcp

Each consumer should pin its MCP configuration to the same design-system version it uses. Avoid pointing consumers at a floating main or latest deployment.

A single gateway could route versioned paths to separate Storybook builds, but changing the /mcp pathname alone is not enough—the underlying stories and component metadata must also come from that exact release.