diff --git a/packages/api/src/mcp/apps.ts b/packages/api/src/mcp/apps.ts
index eb3aad1f47..a81aa58dad 100644
--- a/packages/api/src/mcp/apps.ts
+++ b/packages/api/src/mcp/apps.ts
@@ -23,7 +23,7 @@ interface McpUiToolMeta {
 
 export const RESOURCE_URI_META_KEY = 'ui/resourceUri';
 
-export const RESOURCE_MIME_TYPE = MCP_APP_MIME_TYPE;
+export const RESOURCE_MIME_TYPE: string = MCP_APP_MIME_TYPE;
 
 export function getToolUiResourceUri(tool: ToolWithMeta): string | undefined {
   const uiMeta = tool._meta?.ui as McpUiToolMeta | undefined;