feat(mcp): advertise server title, description, website, and icon (#3394)

## Summary

MCP directories and clients score servers on the `Implementation` metadata in the initialize response ([spec 2026-07-28: Implementation](https://modelcontextprotocol.io/specification/2026-07-28/schema#implementation), [Icon](https://modelcontextprotocol.io/specification/2026-07-28/schema#icon)): a human-readable title, a useful description, a public website, and a scalable or >=128px icon. We only sent `name` and `version`.

This adds to the MCP server's `serverInfo`:

- `title`: "ClickStack"
- `description`: a short summary of what the server does
- `websiteUrl`: the ClickStack docs
- `icons`: the HyperDX logo SVG (`sizes: ["any"]`), served by the app at `${FRONTEND_URL}/favicons/hyperdx/favicon.svg`. Omitted when `FRONTEND_URL` is unset, since icon sources must be absolute URLs

Instructions and capabilities are unchanged. All fields exist on the SDK 1.29 `Implementation` type. Covered by `packages/api/src/mcp/__tests__/serverMetadata.test.ts`.

### How to reproduce

**Starting point:** local full stack via `yarn dev` (the MCP server needs the API).

**On `main`:**

1. Run `yarn dev`.
2. Run `npx @modelcontextprotocol/inspector` and connect it to the local MCP endpoint (see `MCP.md`).
3. Check the initialize response: `serverInfo` has only `name` and `version`.

**On this branch:**

1. Repeat the steps above.
2. `serverInfo` now also has `title`, `description`, `websiteUrl`, and `icons`. `tools/list` and instructions match `main`.

### References

- Linear Issue:
- Related PRs:

Author: brandon-pereira

.changeset/mcp-server-metadata.md

@@ -0,0 +1,5 @@
+---
+'@hyperdx/api': patch
+---
+
+feat(mcp): advertise a title, description, website URL, and SVG icon in the MCP server's initialize response

packages/api/src/mcp/__tests__/serverMetadata.test.ts

@@ -0,0 +1,57 @@
+import type { Implementation } from '@modelcontextprotocol/sdk/types.js';
+
+import { McpContext } from '@/mcp/tools/types';
+
+const context: McpContext = { teamId: 'team-id', userId: 'user-id' };
+
+async function getServerInfo(
+  frontendUrl: string,
+): Promise<Implementation | undefined> {
+  let createTestClient!: typeof import('./mcpTestUtils').createTestClient;
+  jest.isolateModules(() => {
+    jest.doMock('@/config', () => ({
+      ...jest.requireActual('@/config'),
+      FRONTEND_URL: frontendUrl,
+    }));
+    ({ createTestClient } =
+      jest.requireActual<typeof import('./mcpTestUtils')>('./mcpTestUtils'));
+  });
+  jest.dontMock('@/config');
+  const client = await createTestClient(context);
+  return client.getServerVersion();
+}
+
+describe('MCP server metadata', () => {
+  it('advertises a title, description, website, and app-hosted icon', async () => {
+    const info = await getServerInfo('https://app.example.com/');
+
+    expect(info).toMatchObject({
+      name: 'clickstack',
+      title: 'ClickStack',
+      websiteUrl: expect.stringMatching(/^https:\/\//),
+      description: expect.any(String),
+    });
+    expect(info?.icons).toEqual([
+      {
+        src: 'https://app.example.com/favicons/hyperdx/favicon.svg',
+        mimeType: 'image/svg+xml',
+        sizes: ['any'],
+      },
+    ]);
+  });
+
+  it('keeps the FRONTEND_URL sub-path in the icon URL', async () => {
+    const info = await getServerInfo('https://host.example.com/hyperdx');
+
+    expect(info?.icons?.[0]?.src).toBe(
+      'https://host.example.com/hyperdx/favicons/hyperdx/favicon.svg',
+    );
+  });
+
+  it('omits the icon when FRONTEND_URL is unset', async () => {
+    const info = await getServerInfo('');
+
+    expect(info?.title).toBe('ClickStack');
+    expect(info?.icons).toBeUndefined();
+  });
+});

packages/api/src/mcp/mcpServer.ts

@@ -1,6 +1,7 @@
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
+import type { Implementation } from '@modelcontextprotocol/sdk/types.js';
 
-import { CODE_VERSION } from '@/config';
+import { CODE_VERSION, FRONTEND_URL } from '@/config';
 
 import dashboardPrompts from './prompts/dashboards/index';
 import alertsTools from './tools/alerts/index';
@@ -35,16 +36,33 @@ const SERVER_INSTRUCTIONS = [
   'dashboard authoring.',
 ].join('\n');
 
+// Served by the app; omitted when FRONTEND_URL is unset because MCP icon
+// sources must be absolute URLs. String concatenation (not `new URL`) keeps
+// any sub-path the app is mounted under. The HyperDX logo is intentional.
+const SERVER_ICON_URL = FRONTEND_URL
+  ? `${FRONTEND_URL.replace(/\/+$/, '')}/favicons/hyperdx/favicon.svg`
+  : undefined;
+
+const SERVER_INFO: Implementation = {
+  name: 'clickstack',
+  title: 'ClickStack',
+  version: `${CODE_VERSION}-beta`,
+  description:
+    'Query and investigate logs, metrics, traces, and sessions stored in ' +
+    'ClickHouse, and manage ClickStack dashboards, alerts, data sources, ' +
+    'and saved searches.',
+  websiteUrl: 'https://clickhouse.com/docs/use-cases/observability/clickstack',
+  ...(SERVER_ICON_URL && {
+    icons: [
+      { src: SERVER_ICON_URL, mimeType: 'image/svg+xml', sizes: ['any'] },
+    ],
+  }),
+};
+
 export function createServer(context: McpContext) {
-  const server = new McpServer(
-    {
-      name: 'clickstack',
-      version: `${CODE_VERSION}-beta`,
-    },
-    {
-      instructions: SERVER_INSTRUCTIONS,
-    },
-  );
+  const server = new McpServer(SERVER_INFO, {
+    instructions: SERVER_INSTRUCTIONS,
+  });
 
   const registerTool = createRegisterTool(server, context);
   const registrar = { server, context, registerTool };