From e7a14da1f37f0ddfda9ed62ded7aa76c4a38451e Mon Sep 17 00:00:00 2001
From: Adam Jones <adamj@anthropic.com>
Date: Mon, 29 Sep 2025 17:49:28 +0000
Subject: [PATCH] fix: change Icon.sizes from string to string[]

Updates the Icon schema to match the MCP specification, which defines
sizes as an array of strings rather than a single string. This allows
icons to specify multiple size variants (e.g., ["48x48", "96x96"]).

Also updates the example usage in simpleStreamableHttp.ts to use the
new array format.
---
 src/examples/server/simpleStreamableHttp.ts | 2 +-
 src/types.ts                                | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/examples/server/simpleStreamableHttp.ts b/src/examples/server/simpleStreamableHttp.ts
index 6f1e20080..de420c1cc 100644
--- a/src/examples/server/simpleStreamableHttp.ts
+++ b/src/examples/server/simpleStreamableHttp.ts
@@ -22,7 +22,7 @@ const getServer = () => {
   const server = new McpServer({
     name: 'simple-streamable-http-server',
     version: '1.0.0',
-    icons: [{src: './mcp.svg', sizes: '512x512', mimeType: 'image/svg+xml'}],
+    icons: [{src: './mcp.svg', sizes: ['512x512'], mimeType: 'image/svg+xml'}],
     websiteUrl: 'https://github.com/modelcontextprotocol/typescript-sdk',
   }, { capabilities: { logging: {} } });
 
diff --git a/src/types.ts b/src/types.ts
index 262e3b623..9ca4e4d8a 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -214,9 +214,11 @@ export const IconSchema = z
      */
     mimeType: z.optional(z.string()),
     /**
-     * Optional string specifying icon dimensions (e.g., "48x48 96x96").
+     * Optional array of strings that specify sizes at which the icon can be used.
+     * Each string should be in WxH format (e.g., "48x48", "96x96") or "any" for scalable formats like SVG.
+     * If not provided, the client should assume that the icon can be used at any size.
      */
-    sizes: z.optional(z.string()),
+    sizes: z.optional(z.array(z.string())),
   })
   .passthrough();