diff --git a/packages/cli/src/ui/commands/effort-command.test.ts b/packages/cli/src/ui/commands/effort-command.test.ts
index 9a23998ad7..b14e49b6a7 100644
--- a/packages/cli/src/ui/commands/effort-command.test.ts
+++ b/packages/cli/src/ui/commands/effort-command.test.ts
@@ -106,15 +106,10 @@ describe('effortCommand', () => {
     expect(res).toMatchObject({ messageType: 'error' });
   });
 
-  it('completes tier prefixes', async () => {
-    expect(await effortCommand.completion!(context, 'hi')).toEqual(['high']);
-    expect(await effortCommand.completion!(context, 'x')).toEqual(['xhigh']);
-    expect(await effortCommand.completion!(context, '')).toEqual([
-      'low',
-      'medium',
-      'high',
-      'xhigh',
-      'max',
-    ]);
+  it('does not offer tier autocompletion (tiers are hinted via argumentHint)', () => {
+    // No completion so bare `/effort` opens the picker instead of auto-picking
+    // the first tier; `/effort <tier>` still parses in the action above.
+    expect(effortCommand.completion).toBeUndefined();
+    expect(effortCommand.argumentHint).toBe('[low|medium|high|xhigh|max]');
   });
 });
diff --git a/packages/cli/src/ui/commands/effort-command.ts b/packages/cli/src/ui/commands/effort-command.ts
index 51cf439dd0..edf03c34c6 100644
--- a/packages/cli/src/ui/commands/effort-command.ts
+++ b/packages/cli/src/ui/commands/effort-command.ts
@@ -28,13 +28,14 @@ export const effortCommand: SlashCommand = {
       { tiers: TIER_LIST },
     );
   },
+  // The tiers show up as a placeholder via argumentHint rather than as
+  // autocompletion suggestions: bare `/effort` should open the picker dialog
+  // (no tier auto-selected), while `/effort <tier>` still sets one directly. A
+  // completion function would surface the tiers as submenu-like entries and let
+  // Enter auto-pick the first one, which we don't want here.
   argumentHint: '[low|medium|high|xhigh|max]',
   kind: CommandKind.BUILT_IN,
   supportedModes: ['interactive', 'non_interactive', 'acp'] as const,
-  completion: async (_context, partialArg) => {
-    const prefix = partialArg.trim().toLowerCase();
-    return REASONING_EFFORT_TIERS.filter((tier) => tier.startsWith(prefix));
-  },
   action: async (
     context: CommandContext,
     actionArgs: string,