diff --git a/frontend/src/__tests__/riexchange-automation-settings.test.ts b/frontend/src/__tests__/riexchange-automation-settings.test.ts
index 79b281510..27142b3f2 100644
--- a/frontend/src/__tests__/riexchange-automation-settings.test.ts
+++ b/frontend/src/__tests__/riexchange-automation-settings.test.ts
@@ -240,3 +240,101 @@ describe('loadAutomationSettings: number fields are escaped into value attribute
     expect(value('ri-exchange-lookback')).toBe('30');
   });
 });
+
+// Issue #1689: the caps showed a bare 0 with no help text, which reads as
+// "no limit" while 0 refuses approved exchanges and skips automated ones.
+describe('loadAutomationSettings: every field explains itself (issue #1689)', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  const fieldIDs = [
+    'ri-exchange-enabled',
+    'ri-exchange-mode',
+    'ri-exchange-threshold',
+    'ri-exchange-max-per-exchange',
+    'ri-exchange-max-daily',
+    'ri-exchange-lookback',
+  ];
+
+  const hintFor = (id: string): string => {
+    const describedBy = document.getElementById(id)?.getAttribute('aria-describedby') ?? '';
+    return describedBy ? document.getElementById(describedBy)?.textContent ?? '' : '';
+  };
+
+  const loadWithZeroCaps = async (): Promise<void> => {
+    setupContainer();
+    (api.getRIExchangeConfig as jest.Mock).mockResolvedValueOnce({
+      auto_exchange_enabled: false,
+      mode: 'manual',
+      utilization_threshold: 95,
+      max_payment_per_exchange_usd: 0,
+      max_payment_daily_usd: 0,
+      lookback_days: 30,
+    });
+    await loadAutomationSettings();
+  };
+
+  test.each(fieldIDs)('%s has a visible hint linked by aria-describedby', async (id) => {
+    await loadWithZeroCaps();
+    expect(hintFor(id).trim().length).toBeGreaterThan(20);
+  });
+
+  // The hints are built by concatenation; a dropped space ran two sentences
+  // together ("exchange.A recommendation").
+  test.each(fieldIDs)('%s hint separates its sentences with a space', async (id) => {
+    await loadWithZeroCaps();
+    expect(hintFor(id)).not.toMatch(/[.!?][A-Z]/);
+    expect(hintFor(id)).not.toMatch(/\s{2,}/);
+  });
+
+  test('the Fully Automated warning names the 4-eyes override and keeps the cap guidance', async () => {
+    setupContainer();
+    (api.getRIExchangeConfig as jest.Mock).mockResolvedValueOnce({
+      auto_exchange_enabled: true, mode: 'auto', utilization_threshold: 95,
+      max_payment_per_exchange_usd: 100, max_payment_daily_usd: 500, lookback_days: 30,
+    });
+    await loadAutomationSettings();
+    const banner = document.querySelector('#ri-exchange-warning-slot .warning-message')?.textContent ?? '';
+    expect(banner).toContain('without manual approval, unless Require different approver (4-eyes mode) is on.');
+    expect(banner).toContain('Ensure spending caps are configured properly.');
+  });
+
+  test('the Enable hint says the mode decides whether exchanges are proposed or run', async () => {
+    await loadWithZeroCaps();
+    expect(hintFor('ri-exchange-enabled')).toMatch(/propose or run exchanges/);
+  });
+
+  test.each(['ri-exchange-max-per-exchange', 'ri-exchange-max-daily'])(
+    '%s says what 0 means and that dialog exchanges use their own limit',
+    async (id) => {
+      await loadWithZeroCaps();
+      const hint = hintFor(id);
+      expect(hint).toMatch(/\b0\b/);
+      expect(hint).toMatch(/refused/);
+      expect(hint).toMatch(/Exchange dialog/);
+    },
+  );
+
+  test('the daily cap names its window', async () => {
+    await loadWithZeroCaps();
+    expect(hintFor('ri-exchange-max-daily')).toContain('UTC day');
+  });
+
+  // fourEyesExchangeMode runs every mode as manual while 4-eyes is on.
+  test('the Mode hint says 4-eyes mode overrides Fully Automated', async () => {
+    await loadWithZeroCaps();
+    const hint = hintFor('ri-exchange-mode');
+    expect(hint).toContain('4-eyes');
+    expect(hint).toMatch(/every exchange waits for approval in either mode/);
+  });
+
+  // The per-exchange cap is checked before the mode branch (pkg/exchange
+  // auto.go), so it limits proposals in Manual Approval mode too.
+  test('the per-exchange hint says a higher payment is not proposed in either mode', async () => {
+    await loadWithZeroCaps();
+    const hint = hintFor('ri-exchange-max-per-exchange');
+    expect(hint).toMatch(/not proposed in either mode/);
+    expect(hint).toMatch(/At 0, no exchange with a payment due is proposed/);
+  });
+});
diff --git a/frontend/src/riexchange.ts b/frontend/src/riexchange.ts
index a2395ea44..07f340180 100644
--- a/frontend/src/riexchange.ts
+++ b/frontend/src/riexchange.ts
@@ -1834,7 +1834,9 @@ function buildAutoWarningBanner(): HTMLDivElement {
   const strong = document.createElement('strong');
   strong.textContent = 'Warning:';
   banner.appendChild(strong);
-  banner.appendChild(document.createTextNode(' Fully Automated mode will execute RI exchanges without manual approval. Ensure spending caps are configured properly.'));
+  // fourEyesExchangeMode runs every mode as manual while 4-eyes is on.
+  banner.appendChild(document.createTextNode(' Fully Automated mode will execute RI exchanges without manual approval, '
+    + 'unless Require different approver (4-eyes mode) is on. Ensure spending caps are configured properly.'));
   return banner;
 }
 
@@ -1847,6 +1849,34 @@ function numberAttr(value: number | null | undefined): string {
   return escapeHtmlAttr(String(value ?? ''));
 }
 
+// Help text for each Exchange Automation field (issue #1689). The caps only
+// gate scheduled and approved exchanges; executeExchange (the Exchange
+// dialog) uses the limit entered in the dialog. The per-exchange cap is
+// checked before the mode branch (pkg/exchange auto.go), so it limits what
+// is proposed in both modes; approving refuses while either cap is 0
+// (exchangeCapStrings). 4-eyes runs every mode as manual (fourEyesExchangeMode).
+const DIALOG_NOTE = 'Exchanges started from the Exchange dialog use the limit entered there instead.';
+const AUTOMATION_HINTS: Record<string, string> = {
+  'ri-exchange-enabled': 'Lets CUDly check convertible RI utilization on its schedule and propose or run exchanges for underutilized RIs, depending on the mode below.',
+  'ri-exchange-mode': 'Manual Approval queues each proposed exchange for someone to approve. Fully Automated runs it without approval, within the payment limits below. '
+    + 'While Require different approver (4-eyes mode) is on, every exchange waits for approval in either mode.',
+  'ri-exchange-threshold': 'Convertible RIs whose utilization over the lookback window is below this percentage are candidates for an exchange.',
+  'ri-exchange-max-per-exchange': 'Largest payment due allowed for one scheduled or approved exchange. A recommendation with a higher payment due is not proposed in either mode. '
+    + 'At 0, no exchange with a payment due is proposed, and approving any exchange is refused. ' + DIALOG_NOTE,
+  'ri-exchange-max-daily': 'Total payment due allowed per UTC day across scheduled and approved exchanges. '
+    + 'At 0, Fully Automated exchanges with a payment due do not run, and approving any exchange is refused. ' + DIALOG_NOTE,
+  'ri-exchange-lookback': 'Days of utilization history used to judge whether a convertible RI is underutilized.',
+};
+
+// One settings row; the control must carry aria-describedby="<id>-hint".
+function automationRow(id: string, label: string, controlHTML: string): string {
+  return '<div class="setting-row">'
+    + '<div class="setting-info"><label for="' + id + '">' + escapeHtml(label) + '</label>'
+    + '<p class="setting-hint" id="' + id + '-hint">' + escapeHtml(AUTOMATION_HINTS[id]) + '</p></div>'
+    + '<div class="setting-input">' + controlHTML + '</div>'
+    + '</div>';
+}
+
 function renderAutomationSettings(container: HTMLElement, config: RIExchangeConfig): void {
   const modeOptions = Object.entries(MODE_LABELS)
     .map(([value, label]) => {
@@ -1861,33 +1891,21 @@ function renderAutomationSettings(container: HTMLElement, config: RIExchangeConf
     + '<fieldset class="settings-category">'
     + '<legend>Exchange Automation</legend>'
     + '<div id="ri-exchange-warning-slot"></div>'
-    + '<div class="setting-row">'
-    +   '<div class="setting-info"><label for="ri-exchange-enabled">Enable Automated Exchange</label></div>'
-    +   '<div class="setting-input"><label class="toggle-label">'
-    +     '<input type="checkbox" id="ri-exchange-enabled"' + (config.auto_exchange_enabled ? ' checked' : '') + '>'
-    +     '<span class="slider"></span>'
-    +   '</label></div>'
-    + '</div>'
-    + '<div class="setting-row">'
-    +   '<div class="setting-info"><label for="ri-exchange-mode">Mode</label></div>'
-    +   '<div class="setting-input"><select id="ri-exchange-mode">' + modeOptions + '</select></div>'
-    + '</div>'
-    + '<div class="setting-row">'
-    +   '<div class="setting-info"><label for="ri-exchange-threshold">Utilization Threshold (%)</label></div>'
-    +   '<div class="setting-input"><input type="number" id="ri-exchange-threshold" value="' + numberAttr(config.utilization_threshold) + '" min="0" max="100" step="0.1"></div>'
-    + '</div>'
-    + '<div class="setting-row">'
-    +   '<div class="setting-info"><label for="ri-exchange-max-per-exchange">Max Payment Per Exchange (USD)</label></div>'
-    +   '<div class="setting-input"><input type="number" id="ri-exchange-max-per-exchange" value="' + numberAttr(config.max_payment_per_exchange_usd) + '" min="0" step="0.01"></div>'
-    + '</div>'
-    + '<div class="setting-row">'
-    +   '<div class="setting-info"><label for="ri-exchange-max-daily">Max Payment Daily (USD)</label></div>'
-    +   '<div class="setting-input"><input type="number" id="ri-exchange-max-daily" value="' + numberAttr(config.max_payment_daily_usd) + '" min="0" step="0.01"></div>'
-    + '</div>'
-    + '<div class="setting-row">'
-    +   '<div class="setting-info"><label for="ri-exchange-lookback">Lookback Days</label></div>'
-    +   '<div class="setting-input"><input type="number" id="ri-exchange-lookback" value="' + numberAttr(config.lookback_days) + '" min="1" max="365"></div>'
-    + '</div>'
+    + automationRow('ri-exchange-enabled', 'Enable Automated Exchange',
+        '<label class="toggle-label">'
+        + '<input type="checkbox" id="ri-exchange-enabled" aria-describedby="ri-exchange-enabled-hint"' + (config.auto_exchange_enabled ? ' checked' : '') + '>'
+        + '<span class="slider"></span>'
+        + '</label>')
+    + automationRow('ri-exchange-mode', 'Mode',
+        '<select id="ri-exchange-mode" aria-describedby="ri-exchange-mode-hint">' + modeOptions + '</select>')
+    + automationRow('ri-exchange-threshold', 'Utilization Threshold (%)',
+        '<input type="number" id="ri-exchange-threshold" aria-describedby="ri-exchange-threshold-hint" value="' + numberAttr(config.utilization_threshold) + '" min="0" max="100" step="0.1">')
+    + automationRow('ri-exchange-max-per-exchange', 'Max Payment Per Exchange (USD)',
+        '<input type="number" id="ri-exchange-max-per-exchange" aria-describedby="ri-exchange-max-per-exchange-hint" value="' + numberAttr(config.max_payment_per_exchange_usd) + '" min="0" step="0.01">')
+    + automationRow('ri-exchange-max-daily', 'Max Payment Daily (USD)',
+        '<input type="number" id="ri-exchange-max-daily" aria-describedby="ri-exchange-max-daily-hint" value="' + numberAttr(config.max_payment_daily_usd) + '" min="0" step="0.01">')
+    + automationRow('ri-exchange-lookback', 'Lookback Days',
+        '<input type="number" id="ri-exchange-lookback" aria-describedby="ri-exchange-lookback-hint" value="' + numberAttr(config.lookback_days) + '" min="1" max="365">')
     + '</fieldset>'
     + '<div id="ri-exchange-settings-message" class="mt-3"></div>'
     + '</form>';