diff --git a/docs/agents/url-change.md b/docs/agents/url-change.md
index 0292eec..515e3a4 100644
--- a/docs/agents/url-change.md
+++ b/docs/agents/url-change.md
@@ -20,6 +20,7 @@ runtime/src/urls.ts                      ← 用户面控制台 URL(cn-only)
   BAILIAN_CONSOLE           BAILIAN_CONSOLE_ROOT/cn-beijing
   API_KEY_PAGE              BAILIAN_CONSOLE/?tab=app#/api-key
   TOKEN_PLAN_PAGE           BAILIAN_CONSOLE_ROOT/cn-beijing?tab=plan#/efm/subscription/overview
+  MCP_WEBSEARCH_PAGE        BAILIAN_CONSOLE?tab=mcp#/mcp-market/detail/WebSearch
 
 core/files/upload.ts                     ← 文件上传 endpoint(cn-pinned)
   UPLOAD_API                ${REGIONS.cn}/api/v1/uploads
diff --git a/packages/commands/src/commands/search/web-activate-hint.ts b/packages/commands/src/commands/search/web-activate-hint.ts
new file mode 100644
index 0000000..6f5d93e
--- /dev/null
+++ b/packages/commands/src/commands/search/web-activate-hint.ts
@@ -0,0 +1,34 @@
+import { BailianError } from "bailian-cli-core";
+import { MCP_WEBSEARCH_PAGE } from "bailian-cli-runtime";
+
+/** recoginze WebSearch MCP not activated / invalid caused 404 (CLI wrapped message from server)。 */
+export function isWebSearchMcpNotActivated(error: unknown): boolean {
+  if (!(error instanceof BailianError)) return false;
+  const message = error.message;
+  if (!/MCP request failed:\s*404\b/i.test(message)) return false;
+  return /未开通|MCP不存在|MCP_IS_INVALID/i.test(message);
+}
+
+/** activate hint; URL from runtime/urls.ts。 */
+export function webSearchActivateHint(): string {
+  return [
+    "Activate (or re-activate) the WebSearch MCP in the Bailian MCP marketplace, then retry.",
+    "If it was previously on SSE, cancel and activate again to upgrade to Streamable HTTP.",
+    `Open: ${MCP_WEBSEARCH_PAGE}`,
+  ].join("\n");
+}
+
+/**
+ * keep original message / exitCode for not activated errors, add hint only; other errors throw as is.
+ * do not replace server error message.
+ */
+export function rethrowWithWebSearchActivateHint(error: unknown): never {
+  if (isWebSearchMcpNotActivated(error) && error instanceof BailianError && !error.hint) {
+    throw new BailianError(error.message, error.exitCode, webSearchActivateHint(), {
+      cause: error,
+      api: error.api,
+      rawResponse: error.rawResponse,
+    });
+  }
+  throw error;
+}
diff --git a/packages/commands/src/commands/search/web.ts b/packages/commands/src/commands/search/web.ts
index 9804527..b294ea2 100644
--- a/packages/commands/src/commands/search/web.ts
+++ b/packages/commands/src/commands/search/web.ts
@@ -5,8 +5,8 @@ import {
   mcpWebSearchPath,
   type FlagsDef,
 } from "bailian-cli-core";
-import { createSpinner } from "bailian-cli-runtime";
-import { emitResult } from "bailian-cli-runtime";
+import { createSpinner, emitResult } from "bailian-cli-runtime";
+import { rethrowWithWebSearchActivateHint } from "./web-activate-hint.ts";
 
 const WEB_SEARCH_FLAGS = {
   query: { type: "string", valueHint: "<text>", description: "Search query text" },
@@ -41,11 +41,14 @@ export default defineCommand({
         return;
       }
 
-      const client = ctx.client.mcp(mcpWebSearchPath());
-      await client.initialize();
-      const tools = await client.listTools();
-
-      emitResult({ tools }, format);
+      try {
+        const client = ctx.client.mcp(mcpWebSearchPath());
+        await client.initialize();
+        const tools = await client.listTools();
+        emitResult({ tools }, format);
+      } catch (error) {
+        rethrowWithWebSearchActivateHint(error);
+      }
       return;
     }
 
@@ -123,7 +126,7 @@ export default defineCommand({
       }
     } catch (error) {
       spinner.stop("Failed.");
-      throw error;
+      rethrowWithWebSearchActivateHint(error);
     }
   },
 });
diff --git a/packages/commands/tests/search-web-activate-hint.test.ts b/packages/commands/tests/search-web-activate-hint.test.ts
new file mode 100644
index 0000000..045185c
--- /dev/null
+++ b/packages/commands/tests/search-web-activate-hint.test.ts
@@ -0,0 +1,81 @@
+import { describe, expect, test } from "vite-plus/test";
+import { BailianError, ExitCode } from "bailian-cli-core";
+import { MCP_WEBSEARCH_PAGE } from "bailian-cli-runtime";
+import {
+  isWebSearchMcpNotActivated,
+  rethrowWithWebSearchActivateHint,
+  webSearchActivateHint,
+} from "../src/commands/search/web-activate-hint.ts";
+
+describe("web-activate-hint", () => {
+  test("识别 404 + 未开通 / MCP不存在 / MCP_IS_INVALID", () => {
+    expect(
+      isWebSearchMcpNotActivated(
+        new BailianError("MCP request failed: 404 Not Found - MCP不存在或未开通"),
+      ),
+    ).toBe(true);
+    expect(
+      isWebSearchMcpNotActivated(new BailianError("MCP request failed: 404  - MCP不存在或未开通")),
+    ).toBe(true);
+    expect(
+      isWebSearchMcpNotActivated(
+        new BailianError("MCP request failed: 404 Not Found - MCP_IS_INVALID"),
+      ),
+    ).toBe(true);
+  });
+
+  test("裸 404 或非 MCP 错误不加开通判定", () => {
+    expect(isWebSearchMcpNotActivated(new BailianError("MCP request failed: 404 Not Found"))).toBe(
+      false,
+    );
+    expect(
+      isWebSearchMcpNotActivated(new BailianError("MCP request failed: 405 Method Not Allowed")),
+    ).toBe(false);
+    expect(isWebSearchMcpNotActivated(new Error("MCP不存在或未开通"))).toBe(false);
+  });
+
+  test("hint 含 MCP 广场 WebSearch 深链", () => {
+    expect(webSearchActivateHint()).toContain(MCP_WEBSEARCH_PAGE);
+    expect(webSearchActivateHint()).toMatch(/Activate|re-activate/i);
+  });
+
+  test("rethrow 保留原 message，补 Hint", () => {
+    const original = new BailianError(
+      "MCP request failed: 404 Not Found - MCP不存在或未开通",
+      ExitCode.GENERAL,
+    );
+    try {
+      rethrowWithWebSearchActivateHint(original);
+      expect.unreachable("should throw");
+    } catch (error) {
+      expect(error).toBeInstanceOf(BailianError);
+      const wrapped = error as BailianError;
+      expect(wrapped.message).toBe(original.message);
+      expect(wrapped.exitCode).toBe(ExitCode.GENERAL);
+      expect(wrapped.hint).toContain(MCP_WEBSEARCH_PAGE);
+      expect(wrapped.cause).toBe(original);
+    }
+  });
+
+  test("已有 hint 或非未开通错误原样抛出", () => {
+    const withHint = new BailianError(
+      "MCP request failed: 404 Not Found - MCP不存在或未开通",
+      ExitCode.GENERAL,
+      "already hinted",
+    );
+    try {
+      rethrowWithWebSearchActivateHint(withHint);
+      expect.unreachable("should throw");
+    } catch (error) {
+      expect(error).toBe(withHint);
+    }
+
+    const other = new BailianError("MCP request failed: 401 Unauthorized");
+    try {
+      rethrowWithWebSearchActivateHint(other);
+      expect.unreachable("should throw");
+    } catch (error) {
+      expect(error).toBe(other);
+    }
+  });
+});
diff --git a/packages/runtime/src/index.ts b/packages/runtime/src/index.ts
index 4db579c..7556c7a 100644
--- a/packages/runtime/src/index.ts
+++ b/packages/runtime/src/index.ts
@@ -34,6 +34,7 @@ export {
   BAILIAN_CONSOLE,
   API_KEY_PAGE,
   TOKEN_PLAN_PAGE,
+  MCP_WEBSEARCH_PAGE,
   VOICE_TTS_PAGE,
 } from "./urls.ts";
 
diff --git a/packages/runtime/src/urls.ts b/packages/runtime/src/urls.ts
index 60a3b33..c230fe0 100644
--- a/packages/runtime/src/urls.ts
+++ b/packages/runtime/src/urls.ts
@@ -18,5 +18,11 @@ export const API_KEY_PAGE = `${BAILIAN_CONSOLE}/?tab=app#/api-key`;
 /** Direct deep link to the Token Plan subscription overview and API key entry. */
 export const TOKEN_PLAN_PAGE = `${BAILIAN_CONSOLE_ROOT}/cn-beijing?tab=plan#/efm/subscription/overview`;
 
+/**
+ * MCP marketplace detail for the built-in WebSearch server.
+ * Users must activate (or re-activate for Streamable HTTP) before `search web` works.
+ */
+export const MCP_WEBSEARCH_PAGE = `${BAILIAN_CONSOLE}?tab=mcp#/mcp-market/detail/WebSearch`;
+
 /** Voice TTS experience center — browse system and custom voices. */
 export const VOICE_TTS_PAGE = "https://help.aliyun.com/zh/model-studio/cosyvoice-voice-list";