From 4434bab19235d1f87f90c6dd006be37202003fcf Mon Sep 17 00:00:00 2001
From: Yanhu007 <huangfuyang900204@gmail.com>
Date: Sun, 12 Apr 2026 00:21:26 +0000
Subject: [PATCH 1/2] fix: support icons in registerTool config and tools/list
 response

The MCP spec's ToolSchema includes icons (via IconsSchema), but
McpServer.registerTool() did not accept icons in its config parameter,
and the tools/list handler did not include icons in the tool definition.

- Add icons to registerTool config type
- Pass icons through _createRegisteredTool
- Include icons in the tools/list response toolDefinition
- Add icons to RegisteredTool type

Fixes #1864
---
 packages/server/src/server/mcp.ts | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/packages/server/src/server/mcp.ts b/packages/server/src/server/mcp.ts
index 6c2699997..bd0a52fc8 100644
--- a/packages/server/src/server/mcp.ts
+++ b/packages/server/src/server/mcp.ts
@@ -146,6 +146,7 @@ export class McpServer {
                                 : EMPTY_OBJECT_JSON_SCHEMA,
                             annotations: tool.annotations,
                             execution: tool.execution,
+                            icons: tool.icons,
                             _meta: tool._meta
                         };
 
@@ -773,7 +774,8 @@ export class McpServer {
         annotations: ToolAnnotations | undefined,
         execution: ToolExecution | undefined,
         _meta: Record<string, unknown> | undefined,
-        handler: AnyToolHandler<StandardSchemaWithJSON | undefined>
+        handler: AnyToolHandler<StandardSchemaWithJSON | undefined>,
+        icons?: Tool['icons'],
     ): RegisteredTool {
         // Validate tool name according to SEP specification
         validateAndWarnToolName(name);
@@ -788,6 +790,7 @@ export class McpServer {
             outputSchema,
             annotations,
             execution,
+            icons,
             _meta,
             handler: handler,
             executor: createToolExecutor(inputSchema, handler),
@@ -870,6 +873,7 @@ export class McpServer {
             inputSchema?: InputArgs;
             outputSchema?: OutputArgs;
             annotations?: ToolAnnotations;
+            icons?: Tool['icons'];
             _meta?: Record<string, unknown>;
         },
         cb: ToolCallback<InputArgs>
@@ -878,7 +882,7 @@ export class McpServer {
             throw new Error(`Tool ${name} is already registered`);
         }
 
-        const { title, description, inputSchema, outputSchema, annotations, _meta } = config;
+        const { title, description, inputSchema, outputSchema, annotations, icons, _meta } = config;
 
         return this._createRegisteredTool(
             name,
@@ -889,7 +893,8 @@ export class McpServer {
             annotations,
             { taskSupport: 'forbidden' },
             _meta,
-            cb as ToolCallback<StandardSchemaWithJSON | undefined>
+            cb as ToolCallback<StandardSchemaWithJSON | undefined>,
+            icons,
         );
     }
 
@@ -1096,6 +1101,7 @@ export type RegisteredTool = {
     outputSchema?: StandardSchemaWithJSON;
     annotations?: ToolAnnotations;
     execution?: ToolExecution;
+    icons?: Tool['icons'];
     _meta?: Record<string, unknown>;
     handler: AnyToolHandler<StandardSchemaWithJSON | undefined>;
     /** @hidden */

From 8c763a271408af3c60fd0625da1a3d3a9d4c1c47 Mon Sep 17 00:00:00 2001
From: Yanhu007 <huangfuyang900204@gmail.com>
Date: Sun, 12 Apr 2026 02:04:24 +0000
Subject: [PATCH 2/2] chore: add changeset for icons fix

---
 .changeset/fix-register-tool-icons.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/fix-register-tool-icons.md

diff --git a/.changeset/fix-register-tool-icons.md b/.changeset/fix-register-tool-icons.md
new file mode 100644
index 000000000..30adf5c89
--- /dev/null
+++ b/.changeset/fix-register-tool-icons.md
@@ -0,0 +1,5 @@
+---
+'@modelcontextprotocol/server': patch
+---
+
+Support `icons` in `McpServer.registerTool()` config and include it in `tools/list` responses. The MCP spec's `ToolSchema` includes `icons` via `IconsSchema`, but the high-level API did not accept or serialize it.