diff --git a/frontend/src/app/pages/AgentChat/parsing/settingsToolMeta.ts b/frontend/src/app/pages/AgentChat/parsing/settingsToolMeta.ts
new file mode 100644
index 00000000..57a2a9d0
--- /dev/null
+++ b/frontend/src/app/pages/AgentChat/parsing/settingsToolMeta.ts
@@ -0,0 +1,73 @@
+// Render an agent's SettingsWrite/SettingsRead so the transcript shows WHAT it
+// touched at a glance, with secrets masked. The agent's raw `changes` input can
+// carry a key it's trying to set, and the generic MCP renderer would paint it; a
+// settings value is the one new place a secret could land on screen, so it's the
+// one place we mask. Mirrors the backend's name rule (redaction.is_secret_field).
+
+const SECRET_NAME_RE = /_(key|token|secret)$/i;
+// Narrow, prefix-anchored so it can't mask a long path or system prompt (those
+// have slashes/spaces); it only catches a real key pasted into a non-secret field.
+const KEYISH_VALUE_RE = /^(sk-|sk-ant-|AIza|ghp_|gho_|github_pat_|xox[baprs]-)/;
+
+export function isSettingsWriteTool(toolName: string): boolean {
+  return /__SettingsWrite$/.test(toolName);
+}
+export function isSettingsReadTool(toolName: string): boolean {
+  return /__SettingsRead$/.test(toolName);
+}
+
+function isSecretField(name: string): boolean {
+  return SECRET_NAME_RE.test(name) || name === 'installation_id';
+}
+
+function maskValue(key: string, value: unknown, cap: number): string {
+  if (isSecretField(key)) return '••••';
+  if (typeof value === 'string') {
+    if (KEYISH_VALUE_RE.test(value.trim())) return '••••';
+    return value.length > cap ? value.slice(0, cap) + '…' : value;
+  }
+  if (value === null || value === undefined) return 'none';
+  return JSON.stringify(value);
+}
+
+const LABELS: Record<string, string> = {
+  default_model: 'Default model',
+  default_mode: 'Default mode',
+  default_system_prompt: 'System prompt',
+  default_thinking_level: 'Thinking level',
+  default_max_turns: 'Max turns',
+  default_folder: 'Default folder',
+  theme: 'Theme',
+  browser_homepage: 'Browser homepage',
+  new_agent_shortcut: 'New-agent shortcut',
+  zoom_sensitivity: 'Zoom sensitivity',
+};
+
+function humanizeKey(key: string): string {
+  return LABELS[key] || key.replace(/_/g, ' ').replace(/^\w/, (ch) => ch.toUpperCase());
+}
+
+interface SettingsChangeRow {
+  label: string;
+  value: string;
+}
+
+function settingsChangeRows(input: unknown, cap: number): SettingsChangeRow[] {
+  const changes = (input as { changes?: unknown })?.changes;
+  if (!changes || typeof changes !== 'object') return [];
+  return Object.entries(changes as Record<string, unknown>)
+    // some models tack a free-form 'reason' onto the args; it isn't a setting.
+    .filter(([k]) => k !== 'reason')
+    .map(([k, v]) => ({ label: humanizeKey(k), value: maskValue(k, v, cap) }));
+}
+
+/** One-line header preview, e.g. "Theme → Light · Default model → Sonnet". */
+export function settingsWriteSummary(input: unknown): string {
+  return settingsChangeRows(input, 40).map((r) => `${r.label} → ${r.value}`).join(' · ');
+}
+
+/** Expanded body: one masked change per line. Replaces the raw-JSON render. */
+export function settingsWriteDisplay(input: unknown): string {
+  const rows = settingsChangeRows(input, 200);
+  return rows.length === 0 ? 'No changes.' : rows.map((r) => `${r.label}: ${r.value}`).join('\n');
+}
diff --git a/frontend/src/app/pages/AgentChat/parsing/toolResultParsing.ts b/frontend/src/app/pages/AgentChat/parsing/toolResultParsing.ts
index 8413c5cf..6e14aff3 100644
--- a/frontend/src/app/pages/AgentChat/parsing/toolResultParsing.ts
+++ b/frontend/src/app/pages/AgentChat/parsing/toolResultParsing.ts
@@ -1,6 +1,7 @@
 import { AgentMessage } from '@/shared/state/agentsSlice';
 import { prettyPath, prettyUrl, quoteQuery, bashCommandDetail } from './toolLabels';
 import { parseMcpToolName, getMcpInputSummary, getGmailHeader } from '@/shared/mcpToolMeta';
+import { isSettingsWriteTool, isSettingsReadTool, settingsWriteSummary, settingsWriteDisplay } from './settingsToolMeta';
 
 export function getToolData(call: AgentMessage) {
   const content = typeof call.content === 'object' ? call.content : {};
@@ -18,6 +19,11 @@ export function isBashTool(name: string) {
 
 export function getInputSummary(toolName: string, input: any): string {
   try {
+    // Settings tool first: legible change list, secrets masked. Must precede the
+    // generic MCP path (it is an MCP tool) or it renders raw changes JSON.
+    if (isSettingsWriteTool(toolName)) return settingsWriteSummary(input);
+    if (isSettingsReadTool(toolName)) return '';
+
     const mcp = parseMcpToolName(toolName);
     if (mcp.isMcp) return getMcpInputSummary(input);
 
@@ -60,6 +66,11 @@ function formatMcpInputDisplay(input: any): string {
 
 export function formatInputDisplay(toolName: string, input: any): string {
   try {
+    // Masked, one-per-line change list instead of raw changes JSON (which would
+    // paint a secret value the agent tried to set).
+    if (isSettingsWriteTool(toolName)) return settingsWriteDisplay(input);
+    if (isSettingsReadTool(toolName)) return '';
+
     const mcp = parseMcpToolName(toolName);
     if (mcp.isMcp) return formatMcpInputDisplay(input);
 
diff --git a/frontend/src/app/pages/AgentChat/tool-bubbles/CompactMcpBubble.tsx b/frontend/src/app/pages/AgentChat/tool-bubbles/CompactMcpBubble.tsx
index fb1c6bb5..4000ef72 100644
--- a/frontend/src/app/pages/AgentChat/tool-bubbles/CompactMcpBubble.tsx
+++ b/frontend/src/app/pages/AgentChat/tool-bubbles/CompactMcpBubble.tsx
@@ -15,6 +15,7 @@ import { GoogleServiceIcon } from '../mcp-cards/GoogleServiceIcon';
 import { ElapsedTimer, formatElapsed } from '../parsing/toolBubbleChrome';
 import { useTermColors } from '../parsing/toolColorize';
 import { ParsedResult } from '../parsing/toolResultParsing';
+import { isSettingsWriteTool, settingsWriteSummary } from '../parsing/settingsToolMeta';
 import { McpToolInfo, getMcpShortAction } from '@/shared/mcpToolMeta';
 import { McpResultCard } from '../mcp-cards/McpResultCard';
 
@@ -56,6 +57,9 @@ export const CompactMcpBubble: React.FC<CompactMcpBubbleProps> = ({
   const ServiceIcon = mcpInfo.isMcp && mcpInfo.service
     ? <GoogleServiceIcon service={mcpInfo.service} size={14} />
     : null;
+  // A grouped settings write shows the masked change list (input-derived, so it
+  // reads even while pending) instead of the generic "Applied: theme" result line.
+  const headerSummary = isSettingsWriteTool(toolName) ? settingsWriteSummary(input) : resultSummary;
 
   return (
     <Box {...selectAttrs} sx={{ my: 0 }}>
@@ -83,7 +87,7 @@ export const CompactMcpBubble: React.FC<CompactMcpBubbleProps> = ({
         >
           {serviceLabel}
         </Typography>
-        {resultSummary && !isError && (
+        {headerSummary && !isError && (
           <Typography
             sx={{
               color: c.text.secondary,
@@ -95,10 +99,10 @@ export const CompactMcpBubble: React.FC<CompactMcpBubbleProps> = ({
                 : { overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }),
             }}
           >
-            {resultSummary}
+            {headerSummary}
           </Typography>
         )}
-        {!resultSummary && !showTimer && <Box sx={{ flex: 1 }} />}
+        {!headerSummary && !showTimer && <Box sx={{ flex: 1 }} />}
         {showTimer && (
           <>
             <Box sx={{ flex: 1 }} />