Merge pull request #159 from modelcontextprotocol/martinalong/mcp-apps/custom-fonts

[MCP Apps] Add way to pass custom fonts

src/spec.types.ts

@@ -284,12 +284,22 @@ export interface McpUiToolCancelledNotification {
   };
 }
 
+/**
+ * @description CSS blocks that can be injected by apps.
+ */
+export interface McpUiHostCss {
+  /** @description CSS for font loading (@font-face rules or @import statements). Apps must apply using applyHostFonts(). */
+  fonts?: string;
+}
+
 /**
  * @description Style configuration for theming MCP apps.
  */
 export interface McpUiHostStyles {
   /** @description CSS variables for theming the app. */
   variables?: McpUiStyles;
+  /** @description CSS blocks that apps can inject. */
+  css?: McpUiHostCss;
 }
 
 /**