Corex MCP

Dev-only Model Context Protocol server for Corex. Exposes read-only tools so AI agents can discover components, modifiers, and themes without grepping the source.

Never enable in production. Upgrading from 0.1.x: Updating Corex.

Requirements

Elixir~> 1.17

Packages

Package	Kind	Purpose	`mix corex.new`
`corex`	Hex dep	Unstyled Phoenix components, hooks, LiveView API	Always
`corex_design`	Hex dep (`runtime: false`)	Config-driven tokens, themes, and component CSS (Design)	On by default; `--no-design` to skip
`corex_mcp`	Hex dep (`only: [:dev, :test]`)	Dev MCP server for AI component and design discovery (MCP); never enable in `:prod`	On by default; `--no-mcp` to skip
`corex_new`	Mix archive	Greenfield generator (`mix corex.new`)	Install once with `mix archive.install hex corex_new`

Installation

corex_mcp does not depend on corex or corex_design. Add those in the host app (the installer does this by default):

def deps do
  [
    {:corex, "~> 0.2"},
    {:corex_design, "~> 0.2", runtime: false, only: :dev},
    {:corex_mcp, "~> 0.2", only: [:dev, :test]}
  ]
end

Mount in your Phoenix endpoint after Plug.Static and before the code reloader:

if Mix.env() in [:dev, :test] do
  plug Corex.MCP
end

Point your MCP client at Phoenix http://localhost:4000/corex/mcp or Tableau http://localhost:4004/corex/mcp. Prefer --no-mcp when scaffolding apps that should not expose the endpoint. Never set allow_remote_access: true casually.

Cursor / Claude Desktop / other clients

mix corex.new / mix corex.tableau.new write a project.cursor/mcp.json with the single URL for that app when --mcp is on (default). For a user-level / shared config (Cursor, Claude Desktop, VS Code, etc.) when you use both hosts, register both servers:

Cursor mcp.json:

{
  "mcpServers": {
    "corex": {
      "url": "http://localhost:4000/corex/mcp"
    },
    "corex-tableau": {
      "url": "http://localhost:4004/corex/mcp"
    }
  }
}

Claude Desktop uses the same two URLs under transport.type: "http". Other streamable HTTP clients: configure Phoenix on 4000 and Tableau on 4004; path is always /corex/mcp.

Canonical guide (tools, security, Tableau Bandit): MCP on Hexdocs / repo guides/MCP.md.

License