diff --git a/packages/app/e2e/browser/workspace-agent-tab-tooltip.spec.ts b/packages/app/e2e/browser/workspace-agent-tab-tooltip.spec.ts
new file mode 100644
index 0000000000..c5870d0134
--- /dev/null
+++ b/packages/app/e2e/browser/workspace-agent-tab-tooltip.spec.ts
@@ -0,0 +1,77 @@
+import type { Locator } from "@playwright/test";
+import { expect, test, type Page } from "../support/fixtures";
+import { createIdleAgent } from "../support/helpers/archive-tab";
+import { seedWorkspace } from "../support/helpers/seed-client";
+import { getServerId } from "../support/helpers/server-id";
+import { waitForWorkspaceTabsVisible } from "../support/helpers/workspace-tabs";
+import { buildHostAgentDetailRoute } from "@/utils/host-routes";
+
+const TITLE_MAX_LENGTH = 80;
+
+function normalizedTitle(title: string): string {
+  return title.replace(/\s+/g, " ").trim();
+}
+
+function expectedTooltipTitle(title: string): string {
+  const singleLineTitle = normalizedTitle(title);
+  return singleLineTitle.length <= TITLE_MAX_LENGTH
+    ? singleLineTitle
+    : `${singleLineTitle.slice(0, TITLE_MAX_LENGTH - 1).trimEnd()}…`;
+}
+
+async function openAgent(page: Page, agent: { id: string; workspaceId: string }): Promise<void> {
+  await page.goto(buildHostAgentDetailRoute(getServerId(), agent.id, agent.workspaceId));
+  await page.waitForURL(
+    (url) => url.pathname.includes("/workspace/") && !url.searchParams.has("open"),
+    { timeout: 60_000 },
+  );
+  await waitForWorkspaceTabsVisible(page);
+}
+
+async function openAgentTabTooltip(page: Page, agentId: string, title: string): Promise<Locator> {
+  await page.getByRole("button", { name: normalizedTitle(title), exact: true }).hover();
+  const tooltip = page.getByTestId(`workspace-tab-tooltip-agent_${agentId}`);
+  await expect(tooltip).toBeVisible({ timeout: 10_000 });
+  return tooltip;
+}
+
+async function expectTwoRowAgentSummary(
+  tooltip: Locator,
+  input: { title: string; agentId: string },
+): Promise<void> {
+  const title = tooltip.getByText(expectedTooltipTitle(input.title), { exact: true });
+  const id = tooltip.getByText(input.agentId.slice(0, 7), { exact: true });
+  const activity = tooltip.getByText(/^(just now|\d+[mhd] ago|[A-Z][a-z]{2} \d{1,2})$/);
+
+  await expect(title).toBeVisible();
+  await expect(id).toBeVisible();
+  await expect(tooltip.getByText("·", { exact: true })).toBeVisible();
+  await expect(activity).toBeVisible();
+  expect((await title.boundingBox())?.y).toBeLessThan((await id.boundingBox())?.y ?? 0);
+}
+
+test.describe("Workspace agent tab tooltip", () => {
+  test("summarizes a multiline agent title above its ID and last activity", async ({ page }) => {
+    test.setTimeout(120_000);
+    const workspace = await seedWorkspace({ repoPrefix: "workspace-agent-tooltip-" });
+
+    try {
+      const title = [
+        "Short first line",
+        "followed by a much longer continuation that should be joined before the complete title is truncated to a useful tooltip length",
+      ].join("\n");
+      const agent = await createIdleAgent(workspace.client, {
+        cwd: workspace.repoPath,
+        workspaceId: workspace.workspaceId,
+        title,
+      });
+
+      await openAgent(page, agent);
+      const tooltip = await openAgentTabTooltip(page, agent.id, title);
+
+      await expectTwoRowAgentSummary(tooltip, { title, agentId: agent.id });
+    } finally {
+      await workspace.cleanup();
+    }
+  });
+});
diff --git a/packages/app/src/screens/workspace/workspace-desktop-tabs-row.tsx b/packages/app/src/screens/workspace/workspace-desktop-tabs-row.tsx
index d7284a22c1..b462cf0cd5 100644
--- a/packages/app/src/screens/workspace/workspace-desktop-tabs-row.tsx
+++ b/packages/app/src/screens/workspace/workspace-desktop-tabs-row.tsx
@@ -68,6 +68,7 @@ import type { Theme } from "@/styles/theme";
 import { RenderProfile } from "@/utils/render-profiler";
 import { TrailingActionScrim } from "@/components/ui/trailing-action-scrim";
 import { useKeyboardActionHandler } from "@/hooks/use-keyboard-action-handler";
+import { useCompactTimeAgo } from "@/hooks/use-compact-time-ago";
 import { buildWorkspaceKeyboardHandlerId } from "@/keyboard/handler-id";
 import type { KeyboardActionDefinition } from "@/keyboard/keyboard-action-dispatcher";
 import { WorkspaceNewTabMenuContent } from "@/screens/workspace/workspace-new-tab-menu";
@@ -81,6 +82,7 @@ import {
   HorizontalScrollBoundaryShades,
   useHorizontalScrollBoundary,
 } from "@/components/ui/horizontal-scroll-boundary";
+import { useSessionStore } from "@/stores/session-store";
 
 const DROPDOWN_WIDTH = 220;
 const DEFAULT_INLINE_ADD_BUTTON_RESERVED_WIDTH = 36;
@@ -108,6 +110,7 @@ const TAB_MIN_WIDTH = 96;
 const TAB_MAX_WIDTH = 160;
 const TAB_CLOSE_BUTTON_RESERVED_WIDTH = 0;
 const TAB_LABEL_LAYOUT_ALLOWANCE = 4;
+const AGENT_TOOLTIP_TITLE_MAX_LENGTH = 80;
 
 const ThemedLoadingSpinner = withUnistyles(LoadingSpinner);
 const ThemedX = withUnistyles(X);
@@ -136,6 +139,56 @@ function updateMeasuredWidth(
   setWidth((current) => retainWorkspaceTabMeasuredWidth(current, nextWidth));
 }
 
+function normalizeAgentTooltipTitle(title: string): string {
+  return title.replace(/\s+/g, " ").trim();
+}
+
+function formatAgentTooltipTitle(singleLineTitle: string): string {
+  if (singleLineTitle.length <= AGENT_TOOLTIP_TITLE_MAX_LENGTH) return singleLineTitle;
+  return `${singleLineTitle.slice(0, AGENT_TOOLTIP_TITLE_MAX_LENGTH - 1).trimEnd()}…`;
+}
+
+function formatAgentTooltipActivity(compactActivity: string): string {
+  if (compactActivity === "now") return "just now";
+  if (/^\d/.test(compactActivity)) return `${compactActivity} ago`;
+  return compactActivity;
+}
+
+function AgentTabTooltipBody({
+  serverId,
+  agentId,
+  title,
+}: {
+  serverId: string;
+  agentId: string;
+  title: string;
+}) {
+  const lastActivityAt = useSessionStore((state) => {
+    const session = state.sessions[serverId];
+    const agent = session?.agents.get(agentId) ?? session?.agentDetails.get(agentId) ?? null;
+    return state.agentLastActivity.get(agentId) ?? agent?.lastActivityAt ?? null;
+  });
+  const compactActivity = useCompactTimeAgo(lastActivityAt);
+  const activity = formatAgentTooltipActivity(compactActivity);
+
+  return (
+    <View style={styles.tooltipAgentContent}>
+      <Text style={styles.agentTooltipTitle} numberOfLines={1} ellipsizeMode="tail">
+        {title}
+      </Text>
+      <View style={styles.tooltipAgentMetadata}>
+        <Text style={styles.tooltipAgentId}>{agentId.slice(0, 7)}</Text>
+        {activity ? (
+          <>
+            <Text style={styles.tooltipAgentSeparator}>·</Text>
+            <Text style={styles.tooltipAgentActivity}>{activity}</Text>
+          </>
+        ) : null}
+      </View>
+    </View>
+  );
+}
+
 function TabLabelMeasurement({
   tabKey,
   label,
@@ -648,6 +701,7 @@ function TabHandleContent({
 }
 
 function TabChip({
+  serverId,
   tab,
   isActive,
   isDragging,
@@ -659,12 +713,14 @@ function TabChip({
   isClosingTab,
   presentation,
   tooltipLabel,
+  accessibilityLabel,
   resolvedTab,
   setHoveredCloseTabKey,
   onNavigateTab,
   onCloseTab,
   dragHandleProps,
 }: {
+  serverId: string;
   tab: WorkspaceTabDescriptor;
   isActive: boolean;
   isDragging: boolean;
@@ -676,6 +732,7 @@ function TabChip({
   isClosingTab: boolean;
   presentation: WorkspaceTabPresentation;
   tooltipLabel: string;
+  accessibilityLabel: string;
   resolvedTab: WorkspaceDesktopTabActions;
   setHoveredCloseTabKey: Dispatch<SetStateAction<string | null>>;
   onNavigateTab: (tabId: string) => void;
@@ -786,7 +843,7 @@ function TabChip({
               onPressIn={handleNavigateTab}
               onPress={handleNavigateTab}
               accessibilityRole="button"
-              accessibilityLabel={tooltipLabel}
+              accessibilityLabel={accessibilityLabel}
               accessibilityState={tabAccessibilityState}
               aria-selected={isActive}
             >
@@ -809,10 +866,11 @@ function TabChip({
             testID={`workspace-tab-tooltip-${testIdentity}`}
           >
             {tab.target.kind === "agent" ? (
-              <View style={styles.tooltipAgentRow}>
-                <Text style={styles.newTabTooltipText}>{tooltipLabel}</Text>
-                <Text style={styles.tooltipAgentId}>{tab.target.agentId.slice(0, 7)}</Text>
-              </View>
+              <AgentTabTooltipBody
+                serverId={serverId}
+                agentId={tab.target.agentId}
+                title={tooltipLabel}
+              />
             ) : (
               <Text style={styles.newTabTooltipText}>{tooltipLabel}</Text>
             )}
@@ -1191,6 +1249,7 @@ function ResolvedWorkspaceDesktopTabsRow({
       return (
         <ResolvedDesktopTabChip
           key={`${item.tab.key}:${item.tab.kind}`}
+          serverId={normalizedServerId}
           item={item}
           isFocused={isFocused}
           isDragging={isActive}
@@ -1223,6 +1282,7 @@ function ResolvedWorkspaceDesktopTabsRow({
       isFocused,
       layout.closeButtonPolicy,
       layout.items,
+      normalizedServerId,
       onCloseOtherTabs,
       onCloseTab,
       onCloseTabsToLeft,
@@ -1336,6 +1396,7 @@ function ResolvedWorkspaceDesktopTabsRow({
   return <RenderProfile id="WorkspaceDesktopTabsRow">{row}</RenderProfile>;
 }
 function ResolvedDesktopTabChip({
+  serverId,
   item,
   isFocused,
   isDragging,
@@ -1361,6 +1422,7 @@ function ResolvedDesktopTabChip({
   showDropIndicatorBefore,
   showDropIndicatorAfter,
 }: {
+  serverId: string;
   item: ResolvedWorkspaceDesktopTabRowItem;
   isFocused: boolean;
   isDragging: boolean;
@@ -1424,10 +1486,18 @@ function ResolvedDesktopTabChip({
     ],
   );
 
-  const tooltipLabel =
+  const rawTooltipLabel =
     presentation.titleState === "loading"
       ? t("workspace.tabs.loadingAgentTitle")
       : presentation.tooltip;
+  const accessibilityLabel =
+    item.tab.target.kind === "agent"
+      ? normalizeAgentTooltipTitle(rawTooltipLabel)
+      : rawTooltipLabel;
+  const tooltipLabel =
+    item.tab.target.kind === "agent"
+      ? formatAgentTooltipTitle(accessibilityLabel)
+      : rawTooltipLabel;
 
   return (
     <View style={styles.tabSlot}>
@@ -1435,6 +1505,7 @@ function ResolvedDesktopTabChip({
         <View style={[styles.tabDropIndicator, styles.tabDropIndicatorBefore]} />
       ) : null}
       <TabChip
+        serverId={serverId}
         tab={item.tab}
         isActive={item.isActive}
         isDragging={isDragging}
@@ -1446,6 +1517,7 @@ function ResolvedDesktopTabChip({
         isClosingTab={item.isClosingTab}
         presentation={presentation}
         tooltipLabel={tooltipLabel}
+        accessibilityLabel={accessibilityLabel}
         resolvedTab={resolvedTab}
         setHoveredCloseTabKey={setHoveredCloseTabKey}
         onNavigateTab={onNavigateTab}
@@ -1641,15 +1713,31 @@ const styles = StyleSheet.create((theme) => ({
     color: theme.colors.foreground,
     fontSize: theme.fontSize.base,
   },
-  tooltipAgentRow: {
+  tooltipAgentContent: {
+    gap: theme.spacing[0.5],
+    maxWidth: 420,
+  },
+  agentTooltipTitle: {
+    color: theme.colors.foreground,
+    fontSize: theme.fontSize.base,
+  },
+  tooltipAgentMetadata: {
     flexDirection: "row",
     alignItems: "center",
-    gap: theme.spacing[2],
+    gap: theme.spacing[1],
   },
   tooltipAgentId: {
     color: theme.colors.foregroundMuted,
     fontSize: theme.fontSize.sm,
   },
+  tooltipAgentSeparator: {
+    color: theme.colors.foregroundExtraMuted,
+    fontSize: theme.fontSize.sm,
+  },
+  tooltipAgentActivity: {
+    color: theme.colors.foregroundMuted,
+    fontSize: theme.fontSize.sm,
+  },
   menuItemHint: {
     color: theme.colors.foregroundMuted,
     fontSize: theme.fontSize.sm,