diff --git a/packages/ai/src/ai/mcp/business-context-delivery.test.ts b/packages/ai/src/ai/mcp/business-context-delivery.test.ts
index 42a49cecc..da074101a 100644
--- a/packages/ai/src/ai/mcp/business-context-delivery.test.ts
+++ b/packages/ai/src/ai/mcp/business-context-delivery.test.ts
@@ -52,11 +52,12 @@ mock.module("@databuddy/auth", () => ({
 	auth: { api: { getSession: async () => session } },
 }));
 let allowed = true;
+let sites = [site];
 const accessible = mock(async (auth: AccessibleWebsitesAuth) =>
 	allowed &&
 	auth.organizationId === "org-synthetic" &&
 	(auth.apiKey || auth.user)
-		? [site]
+		? sites
 		: []
 );
 mock.module("../../lib/accessible-websites", () => ({
@@ -173,9 +174,74 @@ beforeEach(() => {
 	model.doStreamCalls.length = 0;
 	session = null;
 	allowed = true;
+	sites = [site];
 });
 
 describe("canonical business context at the native shared-agent model boundary", () => {
+	it.each([
+		["Reports.Example.com", "reports.example.com"],
+		["reports.example.com", "REPORTS.EXAMPLE.COM"],
+		["Reports.Example.com", "http://reports.example.com"],
+		["reports.example.com", "HTTPS://REPORTS.EXAMPLE.COM"],
+		["WWW.Example.com", "https://www.example.com"],
+		["Reports.Example.com:8443", "HtTpS://reports.example.com:8443"],
+	])("accepts stored %s selected as %s through ask, stream and trace", async (
+		domain,
+		websiteDomain
+	) => {
+		sites = [{ ...site, domain }];
+		for (const websiteId of [undefined, site.id]) {
+			const input = { ...options, websiteId, websiteDomain };
+			await askDatabuddyAgent(input);
+			await traceDatabuddyAgent(input);
+			for await (const _chunk of streamDatabuddyAgent(input)) {
+				/* consume native stream */
+			}
+		}
+		const calls = [...model.doGenerateCalls, ...model.doStreamCalls];
+		expect(calls).toHaveLength(6);
+		for (const call of calls) {
+			expect(JSON.stringify(call.prompt)).toContain(meaning);
+		}
+		expect(read).toHaveBeenCalledTimes(6);
+		expect(read.mock.calls.every(([id]) => id === "org-synthetic")).toBe(true);
+	});
+	it("retains the selected ID when accessible sites share a normalized domain", async () => {
+		sites = [
+			{ ...site, id: "earlier-site", domain: "REPORTS.EXAMPLE.COM" },
+			{ ...site, domain: "Reports.Example.com" },
+		];
+		await askDatabuddyAgent({
+			...options,
+			websiteId: site.id,
+			websiteDomain: "https://reports.example.com",
+		});
+		expect(JSON.stringify(model.doGenerateCalls[0].prompt)).toContain(meaning);
+		expect(read).toHaveBeenCalledTimes(1);
+	});
+	it("rejects unsupported domain rewrites and mismatched accessible IDs before profile or model access", async () => {
+		sites = [
+			site,
+			{ ...site, id: "other-allowed-site", domain: "other.example.com" },
+		];
+		for (const websiteDomain of [
+			"www.reports.example.com",
+			"reports.example.com/",
+			" https://reports.example.com",
+			"https://reports.example.com/path",
+			"https://reports.example.com.evil.example",
+			"//reports.example.com",
+			"reports.example.com:443",
+			"ftp://reports.example.com",
+			"https://other.example.com",
+		]) {
+			await expect(
+				askDatabuddyAgent({ ...options, websiteId: site.id, websiteDomain })
+			).rejects.toThrow("not accessible");
+		}
+		expect(read).not.toHaveBeenCalled();
+		expect(model.doGenerateCalls).toHaveLength(0);
+	});
 	for (const source of ["slack", "mcp", "dashboard"] as const) {
 		it(`${source}: pairs absent/saved context through ask, stream and trace`, async () => {
 			for (const present of [false, true]) {
diff --git a/packages/ai/src/ai/mcp/run-agent.ts b/packages/ai/src/ai/mcp/run-agent.ts
index a4e934923..ddfb0c8ad 100644
--- a/packages/ai/src/ai/mcp/run-agent.ts
+++ b/packages/ai/src/ai/mcp/run-agent.ts
@@ -12,6 +12,7 @@ import { DatabuddyAgentUserError } from "../../agent/errors";
 import { getAILogger } from "../../lib/ai-logger";
 import { getAccessibleWebsites } from "../../lib/accessible-websites";
 import { loadOrganizationBusinessContext } from "../../lib/organization-business-context";
+import { matchesWebsiteDomain } from "../../lib/website-domain";
 import { mergeWideEvent } from "../../lib/tracing";
 import {
 	ensureAgentCreditsAvailable,
@@ -262,14 +263,15 @@ async function prepareMcpAgentRun(options: RunMcpAgentOptions) {
 		organizationId,
 		user: session?.user.id === mcpUserId ? session.user : null,
 	});
+	const websiteDomain = options.websiteDomain;
 	// A caller-supplied site must not bind another organization's brief or tools.
 	if (
 		(options.websiteId &&
 			!accessibleWebsites.some((site) => site.id === options.websiteId)) ||
-		(options.websiteDomain &&
+		(websiteDomain &&
 			!accessibleWebsites.some(
 				(site) =>
-					site.domain === options.websiteDomain &&
+					matchesWebsiteDomain(site.domain, websiteDomain) &&
 					(!options.websiteId || site.id === options.websiteId)
 			))
 	) {
diff --git a/packages/ai/src/ai/mcp/tool-context.test.ts b/packages/ai/src/ai/mcp/tool-context.test.ts
index a47562830..bc41b77e9 100644
--- a/packages/ai/src/ai/mcp/tool-context.test.ts
+++ b/packages/ai/src/ai/mcp/tool-context.test.ts
@@ -1,6 +1,30 @@
 import { describe, expect, it, mock } from "bun:test";
+import type { WebsiteSummary } from "../../lib/accessible-websites";
 
 const permission = mock(async () => ({ success: true }));
+const sites: WebsiteSummary[] = [
+	{
+		id: "site",
+		domain: "Reports.Example.com",
+		name: "Reports",
+		createdAt: null,
+		isPublic: false,
+	},
+	{
+		id: "www-site",
+		domain: "WWW.Example.com",
+		name: "WWW",
+		createdAt: null,
+		isPublic: false,
+	},
+	{
+		id: "port-site",
+		domain: "Reports.Example.com:8443",
+		name: "Port",
+		createdAt: null,
+		isPublic: false,
+	},
+];
 mock.module("@databuddy/auth", () => ({
 	websitesApi: { hasPermission: permission },
 }));
@@ -12,7 +36,7 @@ mock.module("../../lib/website-utils", () => ({
 	getCachedWebsite: async () => null,
 }));
 mock.module("../../lib/accessible-websites", () => ({
-	getAccessibleWebsites: async () => [],
+	getAccessibleWebsites: async () => sites,
 }));
 mock.module("@databuddy/api-keys/resolve", () => ({
 	hasKeyScope: () => true,
@@ -20,7 +44,36 @@ mock.module("@databuddy/api-keys/resolve", () => ({
 }));
 mock.module("@databuddy/redis", () => ({ getRedisCache: () => null }));
 
-const { ensureWebsiteAccess } = await import("./tool-context");
+const { ensureWebsiteAccess, resolveWebsiteId } = await import("./tool-context");
+
+describe("MCP domain selector compatibility", () => {
+	it.each([
+		["reports.example.com", "site"],
+		["REPORTS.EXAMPLE.COM", "site"],
+		["http://reports.example.com", "site"],
+		["HTTPS://REPORTS.EXAMPLE.COM", "site"],
+		["https://www.example.com", "www-site"],
+		["HtTpS://reports.example.com:8443", "port-site"],
+	])("resolves %s to %s", async (websiteDomain, expected) => {
+		expect(
+			await resolveWebsiteId({ websiteDomain }, { apiKey: null, userId: null })
+		).toBe(expected);
+	});
+	it.each([
+		"www.reports.example.com",
+		"reports.example.com/",
+		" https://reports.example.com",
+		"https://reports.example.com/path",
+		"https://reports.example.com.evil.example",
+		"//reports.example.com",
+		"reports.example.com:443",
+		"ftp://reports.example.com",
+	])("does not rewrite unsupported selector %s", async (websiteDomain) => {
+		expect(
+			await resolveWebsiteId({ websiteDomain }, { apiKey: null, userId: null })
+		).toBeInstanceOf(Error);
+	});
+});
 
 describe("shared agent's business-context organization boundary", () => {
 	it("rejects a site in another organization even if the session could read both", async () => {
diff --git a/packages/ai/src/ai/mcp/tool-context.ts b/packages/ai/src/ai/mcp/tool-context.ts
index e1140e60c..4936a8619 100644
--- a/packages/ai/src/ai/mcp/tool-context.ts
+++ b/packages/ai/src/ai/mcp/tool-context.ts
@@ -11,8 +11,8 @@ import { websitesApi } from "@databuddy/auth";
 import { getRedisCache } from "@databuddy/redis";
 import type { AppContext } from "../config/context";
 import { getCachedWebsite, validateWebsite } from "../../lib/website-utils";
+import { matchesWebsiteDomain } from "../../lib/website-domain";
 
-const PROTOCOL_RE = /^https?:\/\//;
 const ACCESSIBLE_WEBSITES_TTL_SEC = 30;
 const ACCESSIBLE_WEBSITES_KEY_PREFIX = "mcp:accessible_websites:v2:";
 
@@ -135,9 +135,11 @@ export async function resolveWebsiteId(
 
 	const list = await getCachedAccessibleWebsites(principal);
 
-	if (input.websiteDomain) {
-		const domain = input.websiteDomain.toLowerCase().replace(PROTOCOL_RE, "");
-		const match = list.find((w) => w.domain?.toLowerCase() === domain);
+	const domain = input.websiteDomain;
+	if (domain) {
+		const match = list.find((website) =>
+			matchesWebsiteDomain(website.domain, domain)
+		);
 		if (match) {
 			return match.id;
 		}
diff --git a/packages/ai/src/lib/website-domain.ts b/packages/ai/src/lib/website-domain.ts
new file mode 100644
index 000000000..85f6ca5e7
--- /dev/null
+++ b/packages/ai/src/lib/website-domain.ts
@@ -0,0 +1,9 @@
+const PROTOCOL_RE = /^https?:\/\//;
+
+/** Match MCP domain selectors without changing hostname, port or path semantics. */
+export function matchesWebsiteDomain(
+	domain: string | null,
+	input: string
+): boolean {
+	return domain?.toLowerCase() === input.toLowerCase().replace(PROTOCOL_RE, "");
+}