Merge pull request modelcontextprotocol#1965 from koic/add_theme_to_icons_in_overview

[Docs] Add `theme` to `icons` in Base Protocol Overview

Author: jonathanhefner

docs/specification/2025-11-25/basic/index.mdx

@@ -227,6 +227,7 @@ Icons are represented as an array of `Icon` objects, where each icon includes:
   - A data URI with base64-encoded image data
 - `mimeType`: Optional MIME type if the server's type is missing or generic
 - `sizes`: Optional array of size specifications (e.g., `["48x48"]`, `["any"]` for scalable formats like SVG, or `["48x48", "96x96"]` for multiple sizes)
+- `theme`: Optional theme preference (`light` or `dark`) for the icon background
 
 **Required MIME type support:**
 

docs/specification/draft/basic/index.mdx

@@ -227,6 +227,7 @@ Icons are represented as an array of `Icon` objects, where each icon includes:
   - A data URI with base64-encoded image data
 - `mimeType`: Optional MIME type if the server's type is missing or generic
 - `sizes`: Optional array of size specifications (e.g., `["48x48"]`, `["any"]` for scalable formats like SVG, or `["48x48", "96x96"]` for multiple sizes)
+- `theme`: Optional theme preference (`light` or `dark`) for the icon background
 
 **Required MIME type support:**