diff --git a/frontend/src/components/workspace/channels/workspace-channels-list.tsx b/frontend/src/components/workspace/channels/workspace-channels-list.tsx
index bb48a5ef7..68066ed89 100644
--- a/frontend/src/components/workspace/channels/workspace-channels-list.tsx
+++ b/frontend/src/components/workspace/channels/workspace-channels-list.tsx
@@ -34,10 +34,13 @@ function providerCanConnect(provider: ChannelProvider): boolean {
   );
 }
 
-function getProviderDisabledReason(
+function getProviderUnavailableReason(
   provider: ChannelProvider,
   t: ReturnType<typeof useI18n>["t"],
 ): string | undefined {
+  if (provider.unavailable_reason) {
+    return provider.unavailable_reason;
+  }
   if (!provider.enabled) {
     return t.channels.disabled;
   }
@@ -84,6 +87,7 @@ export function WorkspaceChannelsList() {
             connectMutation.isPending &&
             connectMutation.variables === provider.provider;
           const canConnect = providerCanConnect(provider);
+          const unavailableReason = getProviderUnavailableReason(provider, t);
 
           return (
             <SidebarMenuItem key={provider.provider}>
@@ -103,9 +107,14 @@ export function WorkspaceChannelsList() {
                     "h-8 w-24 px-2 text-xs",
                     isConnected && "gap-1",
                   )}
-                  disabled={!canConnect || isPending}
-                  title={getProviderDisabledReason(provider, t)}
+                  disabled={isConnected || isPending}
+                  title={unavailableReason}
                   onClick={() => {
+                    if (!canConnect) {
+                      toast.error(unavailableReason ?? t.channels.unavailable);
+                      return;
+                    }
+
                     const connectWindow =
                       provider.auth_mode === "deep_link"
                         ? prepareConnectWindow()
diff --git a/frontend/src/components/workspace/settings/channels-settings-page.tsx b/frontend/src/components/workspace/settings/channels-settings-page.tsx
index 279de5ddb..0b8bfe08b 100644
--- a/frontend/src/components/workspace/settings/channels-settings-page.tsx
+++ b/frontend/src/components/workspace/settings/channels-settings-page.tsx
@@ -81,10 +81,13 @@ function getStatusLabel(
   return t.channels.notConnected;
 }
 
-function getProviderDisabledReason(
+function getProviderUnavailableReason(
   provider: ChannelProvider,
   t: ReturnType<typeof useI18n>["t"],
 ): string | undefined {
+  if (provider.unavailable_reason) {
+    return provider.unavailable_reason;
+  }
   if (!provider.enabled) {
     return t.channels.disabled;
   }
@@ -116,7 +119,7 @@ function ChannelProviderItem({
     disconnectMutation.variables === connection?.id;
   const connectionLabel = connection ? getConnectionLabel(connection) : null;
   const statusLabel = getStatusLabel(provider, connection, t);
-  const unavailableReason = getProviderDisabledReason(provider, t);
+  const unavailableReason = getProviderUnavailableReason(provider, t);
 
   return (
     <Item variant="outline" className="w-full items-start">
@@ -162,9 +165,14 @@ function ChannelProviderItem({
           <Button
             type="button"
             size="sm"
-            disabled={!canConnect || isConnecting}
+            disabled={isConnecting}
             title={unavailableReason}
             onClick={() => {
+              if (!canConnect) {
+                toast.error(unavailableReason ?? t.channels.unavailable);
+                return;
+              }
+
               const connectWindow =
                 provider.auth_mode === "deep_link"
                   ? prepareConnectWindow()
diff --git a/frontend/tests/e2e/channels.spec.ts b/frontend/tests/e2e/channels.spec.ts
index a522c2d5c..f2b4c7e25 100644
--- a/frontend/tests/e2e/channels.spec.ts
+++ b/frontend/tests/e2e/channels.spec.ts
@@ -12,24 +12,41 @@ const channelProviders = [
   ["wecom", "WeCom", "binding_code"],
 ] as const;
 
-function mockChannelsAPI(page: Page) {
+type MockChannelProvider = {
+  provider: string;
+  display_name: string;
+  enabled: boolean;
+  configured: boolean;
+  connectable: boolean;
+  auth_mode: string;
+  connection_status: string;
+  unavailable_reason?: string | null;
+};
+
+function defaultProviders(): MockChannelProvider[] {
+  return channelProviders.map(([provider, displayName, authMode]) => ({
+    provider,
+    display_name: displayName,
+    enabled: true,
+    configured: true,
+    connectable: true,
+    auth_mode: authMode,
+    connection_status: "not_connected",
+  }));
+}
+
+function mockChannelsAPI(
+  page: Page,
+  providers: MockChannelProvider[] = defaultProviders(),
+  onSlackConnect?: () => void,
+) {
   void page.route("**/api/channels/providers", (route) => {
     return route.fulfill({
       status: 200,
       contentType: "application/json",
       body: JSON.stringify({
         enabled: true,
-        providers: channelProviders.map(
-          ([provider, displayName, authMode]) => ({
-            provider,
-            display_name: displayName,
-            enabled: true,
-            configured: true,
-            connectable: true,
-            auth_mode: authMode,
-            connection_status: "not_connected",
-          }),
-        ),
+        providers,
       }),
     });
   });
@@ -43,6 +60,7 @@ function mockChannelsAPI(page: Page) {
   });
 
   void page.route("**/api/channels/slack/connect", (route) => {
+    onSlackConnect?.();
     return route.fulfill({
       status: 200,
       contentType: "application/json",
@@ -102,4 +120,42 @@ test.describe("IM channels", () => {
       page.getByText("Send /connect abc123 to the DeerFlow Slack bot."),
     ).toBeVisible();
   });
+
+  test("unavailable providers stay clickable and explain what is missing", async ({
+    page,
+  }) => {
+    mockLangGraphAPI(page);
+    const unavailableReason =
+      "Enable and configure channels.slack with channels.slack.bot_token and channels.slack.app_token.";
+    let connectRequests = 0;
+    mockChannelsAPI(
+      page,
+      [
+        {
+          provider: "slack",
+          display_name: "Slack",
+          enabled: true,
+          configured: false,
+          connectable: false,
+          unavailable_reason: unavailableReason,
+          auth_mode: "binding_code",
+          connection_status: "not_connected",
+        },
+      ],
+      () => {
+        connectRequests += 1;
+      },
+    );
+
+    await page.goto("/workspace/chats/new");
+
+    const sidebar = page.locator("[data-sidebar='sidebar']");
+    const connectButton = sidebar.getByRole("button", { name: "Connect" });
+    await expect(connectButton).toBeEnabled({ timeout: 15_000 });
+
+    await connectButton.click();
+
+    await expect(page.getByText(unavailableReason)).toBeVisible();
+    expect(connectRequests).toBe(0);
+  });
 });