Module: McpUiServer

Defined in:

lib/mcp_ui_server.rb,
lib/mcp_ui_server/version.rb

Overview

The McpUiServer module provides helper methods for creating UI resources compatible with the Model Context Protocol UI (mcp-ui) client.

Defined Under Namespace

Classes: Error

Constant Summary

MIME_TYPE_HTML =

MIME type constants

'text/html'

MIME_TYPE_URI_LIST =

'text/uri-list'

MIME_TYPE_REMOTE_DOM =

'application/vnd.mcp-ui.remote-dom+javascript; framework=%s'

CONTENT_TYPE_RAW_HTML =

Content type constants

:raw_html

CONTENT_TYPE_EXTERNAL_URL =

:external_url

CONTENT_TYPE_REMOTE_DOM =

:remote_dom

PROTOCOL_CONTENT_TYPES =

Protocol mapping (snake_case to camelCase for protocol consistency)

{
  raw_html: 'rawHtml',
  external_url: 'externalUrl',
  remote_dom: 'remoteDom'
}.freeze

REQUIRED_CONTENT_KEYS =

Required content keys for each content type

{
  CONTENT_TYPE_RAW_HTML => :htmlString,
  CONTENT_TYPE_EXTERNAL_URL => :iframeUrl,
  CONTENT_TYPE_REMOTE_DOM => :script
}.freeze

UI_URI_SCHEME =

URI scheme constant

'ui://'

VERSION =

'0.1.0'

Class Method Summary

• .create_ui_resource(uri:, content:, encoding: :text) ⇒ Hash

  Creates a UIResource hash structure for an MCP response.

Class Method Details

.create_ui_resource(uri:, content:, encoding: :text) ⇒ Hash

Creates a UIResource hash structure for an MCP response. This structure can then be serialized to JSON by your web framework.

Parameters:

• uri (String) —

  The unique identifier for the resource (e.g., ‘ui://greeting/1’).

• content (Hash) —

  A hash describing the UI content.

  • :type [Symbol] The type of content. One of :raw_html, :external_url, or :remote_dom.

  • :htmlString [String] The raw HTML content (required if type is :raw_html).

  • :iframeUrl [String] The URL for an external page (required if type is :external_url).

  • :script [String] The remote-dom script (required if type is :remote_dom).

  • :framework [Symbol] The remote-dom framework, e.g., :react or :webcomponents (required, for :remote_dom).

• encoding (Symbol) (defaults to: :text) —

  The encoding method. :text for plain string, :blob for base64 encoded.

Returns:

• (Hash) —

  A UIResource hash ready to be included in an MCP response.

Raises:

• (McpUiServer::Error) —

  if URI scheme is invalid, content type is unknown, encoding type is unknown, or required content keys are missing.

# File 'lib/mcp_ui_server.rb', line 54

def self.create_ui_resource(uri:, content:, encoding: :text)
  validate_uri_scheme(uri)

  resource = { uri: uri }

  content_value = process_content(content, resource)
  process_encoding(encoding, resource, content_value)

  {
    type: 'resource',
    resource: resource
  }
end