diff --git a/apps/desktop/src/settings/DesktopClientSettings.test.ts b/apps/desktop/src/settings/DesktopClientSettings.test.ts
index 23a75eb3f79d..d361873d19cc 100644
--- a/apps/desktop/src/settings/DesktopClientSettings.test.ts
+++ b/apps/desktop/src/settings/DesktopClientSettings.test.ts
@@ -25,6 +25,7 @@ const clientSettings: ClientSettings = {
   fontFamilySans: "",
   fontFamilyTerminal: "",
   fontSizeCode: 13,
+  fontSizeToolOutput: 11,
   fontSizeInterface: 16,
   fontSizePrompt: 14,
   fontSizeTerminal: 12,
diff --git a/apps/web/src/appearanceFonts.test.ts b/apps/web/src/appearanceFonts.test.ts
index c82c908207a3..3fbc579e4bc1 100644
--- a/apps/web/src/appearanceFonts.test.ts
+++ b/apps/web/src/appearanceFonts.test.ts
@@ -5,6 +5,7 @@ import {
   clampCodeFontSize,
   clampInterfaceFontSize,
   clampPromptFontSize,
+  clampToolOutputFontSize,
   DEFAULT_CODE_FONT_STACK,
   DEFAULT_SANS_FONT_STACK,
   appearanceFontStack,
@@ -13,6 +14,7 @@ import {
   resolveDefaultFamilyLabel,
   resolveTerminalFontPreference,
   resolveTerminalFontSizePreference,
+  applyAppearanceFontVariables,
 } from "./appearanceFonts";
 
 describe("installed font discovery", () => {
@@ -155,11 +157,41 @@ describe("font size clamping", () => {
     expect(clampInterfaceFontSize(96)).toBe(20);
     expect(clampPromptFontSize(40)).toBe(20);
     expect(clampCodeFontSize(1)).toBe(10);
+    expect(clampToolOutputFontSize(1)).toBe(10);
+    expect(clampToolOutputFontSize(99)).toBe(18);
   });
 
   it("rounds fractional values and falls back for unusable input", () => {
     expect(clampCodeFontSize(13.4)).toBe(13);
     expect(clampInterfaceFontSize(Number.NaN)).toBe(16);
     expect(clampPromptFontSize(Number.POSITIVE_INFINITY)).toBe(14);
+    expect(clampToolOutputFontSize(Number.NaN)).toBe(11);
+  });
+});
+
+describe("appearance font variables", () => {
+  it("emits an independently clamped absolute tool-output size", () => {
+    const setProperty = vi.fn();
+    const root = {
+      style: {
+        fontSize: "",
+        removeProperty: vi.fn(),
+        setProperty,
+      },
+    } as unknown as HTMLElement;
+
+    applyAppearanceFontVariables(root, {
+      sans: "",
+      code: "",
+      composer: "",
+      sizeInterface: 16,
+      sizePrompt: 14,
+      sizeCode: 14,
+      sizeToolOutput: 8,
+      smoothing: true,
+    });
+
+    expect(setProperty).toHaveBeenCalledWith("--font-size-code", "14px");
+    expect(setProperty).toHaveBeenCalledWith("--font-size-tool-output", "10px");
   });
 });
diff --git a/apps/web/src/appearanceFonts.ts b/apps/web/src/appearanceFonts.ts
index 9eda4e3df97a..f21b8491e36a 100644
--- a/apps/web/src/appearanceFonts.ts
+++ b/apps/web/src/appearanceFonts.ts
@@ -9,12 +9,15 @@ import {
   DEFAULT_CODE_FONT_SIZE,
   DEFAULT_INTERFACE_FONT_SIZE,
   DEFAULT_PROMPT_FONT_SIZE,
+  DEFAULT_TOOL_OUTPUT_FONT_SIZE,
   MAX_CODE_FONT_SIZE,
   MAX_INTERFACE_FONT_SIZE,
   MAX_PROMPT_FONT_SIZE,
+  MAX_TOOL_OUTPUT_FONT_SIZE,
   MIN_CODE_FONT_SIZE,
   MIN_INTERFACE_FONT_SIZE,
   MIN_PROMPT_FONT_SIZE,
+  MIN_TOOL_OUTPUT_FONT_SIZE,
 } from "@t3tools/contracts";
 
 export const DEFAULT_SANS_FONT_STACK =
@@ -84,6 +87,7 @@ export interface AppearanceFontPreferences {
   readonly sizeInterface: number;
   readonly sizePrompt: number;
   readonly sizeCode: number;
+  readonly sizeToolOutput: number;
   /** Grayscale `antialiased` rendering; false keeps the heavier platform default. */
   readonly smoothing: boolean;
 }
@@ -119,6 +123,10 @@ export function applyAppearanceFontVariables(
   root.style.setProperty("--font-size-prompt", `${clampPromptFontSize(preferences.sizePrompt)}px`);
   const code = clampCodeFontSize(preferences.sizeCode);
   root.style.setProperty("--font-size-code", `${code}px`);
+  root.style.setProperty(
+    "--font-size-tool-output",
+    `${clampToolOutputFontSize(preferences.sizeToolOutput)}px`,
+  );
   // The @pierre/diffs surfaces read their own hook for code text.
   root.style.setProperty("--diffs-font-size", `${code}px`);
 
@@ -155,6 +163,15 @@ export function clampCodeFontSize(value: number): number {
   return clampFontSize(value, MIN_CODE_FONT_SIZE, MAX_CODE_FONT_SIZE, DEFAULT_CODE_FONT_SIZE);
 }
 
+export function clampToolOutputFontSize(value: number): number {
+  return clampFontSize(
+    value,
+    MIN_TOOL_OUTPUT_FONT_SIZE,
+    MAX_TOOL_OUTPUT_FONT_SIZE,
+    DEFAULT_TOOL_OUTPUT_FONT_SIZE,
+  );
+}
+
 const FONT_PROBE_TEXT = "mmmmmmmmMMWli1O0@# fjord";
 let fontProbeContext: CanvasRenderingContext2D | null | undefined;
 
diff --git a/apps/web/src/components/chat/MessagesTimeline.test.tsx b/apps/web/src/components/chat/MessagesTimeline.test.tsx
index a9e95c2b0f22..a8501e68166d 100644
--- a/apps/web/src/components/chat/MessagesTimeline.test.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.test.tsx
@@ -626,6 +626,24 @@ describe("MessagesTimeline", () => {
     expect(copyControlMarkup).not.toContain("Copy output");
   });
 
+  it("sizes every expanded body block with the tool-output variable", () => {
+    const markup = renderToStaticMarkup(
+      <WorkEntryExpandedBody
+        body={{
+          blocks: [
+            { kind: "output", text: "command output", isError: false, truncated: false },
+            { kind: "empty" },
+            { kind: "text", text: "tool detail" },
+          ],
+        }}
+      />,
+    );
+
+    const toolOutputClass = "text-[length:var(--font-size-tool-output,0.6875rem)]";
+    expect(markup.split(toolOutputClass)).toHaveLength(4);
+    expect(markup).not.toContain("--font-size-code");
+  });
+
   it("renders provider no-output sentinels as the empty state", () => {
     for (const sentinel of [
       "(Bash completed with no output)",
diff --git a/apps/web/src/components/chat/MessagesTimeline.tsx b/apps/web/src/components/chat/MessagesTimeline.tsx
index 00bbfd5690e3..90f97be892c1 100644
--- a/apps/web/src/components/chat/MessagesTimeline.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.tsx
@@ -2308,7 +2308,7 @@ export const WorkEntryExpandedBody = memo(function WorkEntryExpandedBody(props:
       {blocks.map((block) =>
         block.kind === "output" ? (
           <div key={`output:${block.text}`}>
-            <pre className="max-h-64 cursor-text overflow-auto whitespace-pre-wrap break-words font-mono text-[11px] text-foreground/80 leading-relaxed select-text">
+            <pre className="max-h-64 cursor-text overflow-auto whitespace-pre-wrap break-words font-mono text-[length:var(--font-size-tool-output,0.6875rem)] text-foreground/80 leading-relaxed select-text">
               {block.isError ? "Error output\n" : null}
               {block.text}
               {block.truncated ? "\n\nOutput truncated" : null}
@@ -2317,14 +2317,14 @@ export const WorkEntryExpandedBody = memo(function WorkEntryExpandedBody(props:
         ) : block.kind === "empty" ? (
           <p
             key="empty"
-            className="font-mono text-[11px] italic leading-relaxed text-muted-foreground"
+            className="font-mono text-[length:var(--font-size-tool-output,0.6875rem)] italic leading-relaxed text-muted-foreground"
           >
             (No output)
           </p>
         ) : (
           <pre
             key={`text:${block.text}`}
-            className="max-h-64 cursor-text overflow-auto whitespace-pre-wrap break-words font-mono text-secondary-label text-[11px] leading-relaxed select-text"
+            className="max-h-64 cursor-text overflow-auto whitespace-pre-wrap break-words font-mono text-secondary-label text-[length:var(--font-size-tool-output,0.6875rem)] leading-relaxed select-text"
           >
             {block.text}
           </pre>
diff --git a/apps/web/src/components/settings/SettingsPanels.logic.test.ts b/apps/web/src/components/settings/SettingsPanels.logic.test.ts
index ec4ad4ff5875..a757b340923d 100644
--- a/apps/web/src/components/settings/SettingsPanels.logic.test.ts
+++ b/apps/web/src/components/settings/SettingsPanels.logic.test.ts
@@ -27,8 +27,9 @@ describe("typography settings restore", () => {
         ...DEFAULT_UNIFIED_SETTINGS,
         fontSizeInterface: 18,
         fontFamilyCode: "Fira Code",
+        fontSizeToolOutput: 12,
       }),
-    ).toEqual(["Interface font", "Code font"]);
+    ).toEqual(["Interface font", "Code font", "Tool output"]);
   });
 });
 
diff --git a/apps/web/src/components/settings/SettingsPanels.logic.ts b/apps/web/src/components/settings/SettingsPanels.logic.ts
index 39f4f3cdafd6..b3e9df6a7a8c 100644
--- a/apps/web/src/components/settings/SettingsPanels.logic.ts
+++ b/apps/web/src/components/settings/SettingsPanels.logic.ts
@@ -83,6 +83,7 @@ type TypographySettings = Pick<
   | "fontSizeInterface"
   | "fontSizePrompt"
   | "fontSizeCode"
+  | "fontSizeToolOutput"
   | "fontSizeTerminal"
 >;
 
@@ -101,6 +102,9 @@ export function getChangedTypographySettingLabels(settings: TypographySettings):
     settings.fontSizeCode !== DEFAULT_UNIFIED_SETTINGS.fontSizeCode
       ? ["Code font"]
       : []),
+    ...(settings.fontSizeToolOutput !== DEFAULT_UNIFIED_SETTINGS.fontSizeToolOutput
+      ? ["Tool output"]
+      : []),
     ...(settings.fontFamilyTerminal !== DEFAULT_UNIFIED_SETTINGS.fontFamilyTerminal ||
     settings.fontSizeTerminal !== DEFAULT_UNIFIED_SETTINGS.fontSizeTerminal
       ? ["Terminal font"]
diff --git a/apps/web/src/components/settings/SettingsPanels.tsx b/apps/web/src/components/settings/SettingsPanels.tsx
index 6f90e6a02553..08ab356ba01d 100644
--- a/apps/web/src/components/settings/SettingsPanels.tsx
+++ b/apps/web/src/components/settings/SettingsPanels.tsx
@@ -24,12 +24,14 @@ import {
   MAX_GLASS_OPACITY,
   MAX_INTERFACE_FONT_SIZE,
   MAX_PROMPT_FONT_SIZE,
+  MAX_TOOL_OUTPUT_FONT_SIZE,
   MAX_SIDEBAR_AUTO_SETTLE_AFTER_DAYS,
   MAX_TERMINAL_FONT_SIZE,
   MIN_CODE_FONT_SIZE,
   MIN_GLASS_OPACITY,
   MIN_INTERFACE_FONT_SIZE,
   MIN_PROMPT_FONT_SIZE,
+  MIN_TOOL_OUTPUT_FONT_SIZE,
   MIN_SIDEBAR_AUTO_SETTLE_AFTER_DAYS,
   MIN_TERMINAL_FONT_SIZE,
 } from "@t3tools/contracts/settings";
@@ -544,6 +546,7 @@ export function useSettingsRestore(onRestored?: () => void) {
       settings.fontFamilySans,
       settings.fontFamilyTerminal,
       settings.fontSizeCode,
+      settings.fontSizeToolOutput,
       settings.fontSizeInterface,
       settings.fontSizePrompt,
       settings.fontSizeTerminal,
@@ -654,6 +657,7 @@ export function useSettingsRestore(onRestored?: () => void) {
       fontSizeInterface: DEFAULT_UNIFIED_SETTINGS.fontSizeInterface,
       fontSizePrompt: DEFAULT_UNIFIED_SETTINGS.fontSizePrompt,
       fontSizeCode: DEFAULT_UNIFIED_SETTINGS.fontSizeCode,
+      fontSizeToolOutput: DEFAULT_UNIFIED_SETTINGS.fontSizeToolOutput,
       fontSizeTerminal: DEFAULT_UNIFIED_SETTINGS.fontSizeTerminal,
     });
     onRestored?.();
@@ -1243,6 +1247,38 @@ function TerminalFontRow() {
   );
 }
 
+function ToolOutputFontRow() {
+  const settings = usePrimarySettings();
+  const updateSettings = useUpdatePrimarySettings();
+  return (
+    <SettingsRow
+      {...searchableSetting("tool-output-font")}
+      description="Agent command and tool call output in the work log."
+      resetAction={
+        settings.fontSizeToolOutput !== DEFAULT_UNIFIED_SETTINGS.fontSizeToolOutput ? (
+          <SettingResetButton
+            label="tool output font size"
+            onClick={() =>
+              updateSettings({
+                fontSizeToolOutput: DEFAULT_UNIFIED_SETTINGS.fontSizeToolOutput,
+              })
+            }
+          />
+        ) : null
+      }
+      control={
+        <FontSizeSelect
+          label="Tool output font size"
+          min={MIN_TOOL_OUTPUT_FONT_SIZE}
+          max={MAX_TOOL_OUTPUT_FONT_SIZE}
+          value={settings.fontSizeToolOutput}
+          onChange={(fontSizeToolOutput) => updateSettings({ fontSizeToolOutput })}
+        />
+      }
+    />
+  );
+}
+
 function FontSmoothingRow() {
   const settings = usePrimarySettings();
   const updateSettings = useUpdatePrimarySettings();
@@ -1304,6 +1340,7 @@ function FontSettingsGroup() {
       <InterfaceFontRow />
       <PromptFontRow />
       <CodeFontRow />
+      <ToolOutputFontRow />
       <TerminalFontRow />
       <FontSmoothingRow />
     </>
@@ -1341,6 +1378,7 @@ function SimpleFontRows() {
           </>
         }
       />
+      <ToolOutputFontRow />
     </>
   );
 }
@@ -1399,6 +1437,44 @@ function TypographySection() {
   );
 }
 
+function FontSizeSelect({
+  label,
+  min,
+  max,
+  value,
+  onChange,
+}: {
+  label: string;
+  min: number;
+  max: number;
+  value: number;
+  onChange: (value: number) => void;
+}) {
+  return (
+    <Select
+      value={String(value)}
+      onValueChange={(next) => {
+        if (typeof next !== "string") return;
+        const parsed = Number(next);
+        if (Number.isInteger(parsed) && parsed >= min && parsed <= max) {
+          onChange(parsed);
+        }
+      }}
+    >
+      <SelectTrigger className="w-22 shrink-0" aria-label={label}>
+        <SelectValue>{value} px</SelectValue>
+      </SelectTrigger>
+      <SelectPopup align="end" alignItemWithTrigger={false}>
+        {Array.from({ length: max - min + 1 }, (_, index) => min + index).map((px) => (
+          <SelectItem hideIndicator key={px} value={String(px)}>
+            {px} px
+          </SelectItem>
+        ))}
+      </SelectPopup>
+    </Select>
+  );
+}
+
 function FontFamilySettingsRow({
   id,
   title,
@@ -1455,29 +1531,13 @@ function FontFamilySettingsRow({
   const control = (
     <div className="flex w-full items-center gap-2 sm:w-auto">
       <div className="min-w-0 flex-1 sm:w-44 sm:flex-none">{familyControl}</div>
-      <Select
-        value={String(size.value)}
-        onValueChange={(next) => {
-          if (typeof next !== "string") return;
-          const parsed = Number(next);
-          if (Number.isInteger(parsed) && parsed >= size.min && parsed <= size.max) {
-            size.onChange(parsed);
-          }
-        }}
-      >
-        <SelectTrigger className="w-22 shrink-0" aria-label={size.label}>
-          <SelectValue>{size.value} px</SelectValue>
-        </SelectTrigger>
-        <SelectPopup align="end" alignItemWithTrigger={false}>
-          {Array.from({ length: size.max - size.min + 1 }, (_, index) => size.min + index).map(
-            (px) => (
-              <SelectItem hideIndicator key={px} value={String(px)}>
-                {px} px
-              </SelectItem>
-            ),
-          )}
-        </SelectPopup>
-      </Select>
+      <FontSizeSelect
+        label={size.label}
+        min={size.min}
+        max={size.max}
+        value={size.value}
+        onChange={size.onChange}
+      />
     </div>
   );
   return (
diff --git a/apps/web/src/components/settings/settingsSearch.ts b/apps/web/src/components/settings/settingsSearch.ts
index e3aef6705665..2c8bbfd08230 100644
--- a/apps/web/src/components/settings/settingsSearch.ts
+++ b/apps/web/src/components/settings/settingsSearch.ts
@@ -83,6 +83,11 @@ export const SETTINGS_SEARCH_ITEMS = [
     title: "Code font",
     to: "/settings/appearance",
   },
+  {
+    id: "tool-output-font",
+    title: "Tool output",
+    to: "/settings/appearance",
+  },
   {
     id: "terminal-font",
     title: "Terminal font",
diff --git a/apps/web/src/routes/__root.tsx b/apps/web/src/routes/__root.tsx
index bc8f8507b814..99be179d81bd 100644
--- a/apps/web/src/routes/__root.tsx
+++ b/apps/web/src/routes/__root.tsx
@@ -168,6 +168,7 @@ function FontAppearanceSync() {
   const fontSizeInterface = useClientSettings((settings) => settings.fontSizeInterface);
   const fontSizePrompt = useClientSettings((settings) => settings.fontSizePrompt);
   const fontSizeCode = useClientSettings((settings) => settings.fontSizeCode);
+  const fontSizeToolOutput = useClientSettings((settings) => settings.fontSizeToolOutput);
   const fontSmoothing = useClientSettings((settings) => settings.fontSmoothing);
 
   useEffect(() => {
@@ -178,6 +179,7 @@ function FontAppearanceSync() {
       sizeInterface: fontSizeInterface,
       sizePrompt: fontSizePrompt,
       sizeCode: fontSizeCode,
+      sizeToolOutput: fontSizeToolOutput,
       smoothing: fontSmoothing,
     });
     for (const family of new Set([fontFamilySans, fontFamilyCode, fontFamilyComposer])) {
@@ -195,6 +197,7 @@ function FontAppearanceSync() {
     fontFamilyComposer,
     fontFamilySans,
     fontSizeCode,
+    fontSizeToolOutput,
     fontSizeInterface,
     fontSizePrompt,
     fontSmoothing,
diff --git a/packages/contracts/src/settings.test.ts b/packages/contracts/src/settings.test.ts
index 570157292b54..f578f7ef7834 100644
--- a/packages/contracts/src/settings.test.ts
+++ b/packages/contracts/src/settings.test.ts
@@ -49,6 +49,22 @@ describe("ClientSettings glass opacity", () => {
   });
 });
 
+describe("ClientSettings tool output font size", () => {
+  it("defaults to 11px", () => {
+    expect(decodeClientSettings({}).fontSizeToolOutput).toBe(11);
+  });
+
+  it.each([9, 19, 11.5])("rejects a size outside the supported integer range: %s", (value) => {
+    expect(() => decodeClientSettings({ fontSizeToolOutput: value })).toThrow();
+    expect(() => decodeClientSettingsPatch({ fontSizeToolOutput: value })).toThrow();
+  });
+
+  it.each([10, 11, 18])("accepts a size within the supported range: %s", (value) => {
+    expect(decodeClientSettings({ fontSizeToolOutput: value }).fontSizeToolOutput).toBe(value);
+    expect(decodeClientSettingsPatch({ fontSizeToolOutput: value }).fontSizeToolOutput).toBe(value);
+  });
+});
+
 describe("ClientSettings environment identification", () => {
   it("defaults to artwork and accepts each presentation mode", () => {
     expect(decodeClientSettings({}).environmentIdentificationMode).toBe("artwork");
diff --git a/packages/contracts/src/settings.ts b/packages/contracts/src/settings.ts
index 9306e430b6e1..8a60280a13f8 100644
--- a/packages/contracts/src/settings.ts
+++ b/packages/contracts/src/settings.ts
@@ -92,6 +92,14 @@ export const CodeFontSize = Schema.Int.check(
 export type CodeFontSize = typeof CodeFontSize.Type;
 export const DEFAULT_CODE_FONT_SIZE: CodeFontSize = 13;
 
+export const MIN_TOOL_OUTPUT_FONT_SIZE = 10;
+export const MAX_TOOL_OUTPUT_FONT_SIZE = 18;
+export const ToolOutputFontSize = Schema.Int.check(
+  Schema.isBetween({ minimum: MIN_TOOL_OUTPUT_FONT_SIZE, maximum: MAX_TOOL_OUTPUT_FONT_SIZE }),
+);
+export type ToolOutputFontSize = typeof ToolOutputFontSize.Type;
+export const DEFAULT_TOOL_OUTPUT_FONT_SIZE: ToolOutputFontSize = 11;
+
 export const MIN_TERMINAL_FONT_SIZE = 8;
 export const MAX_TERMINAL_FONT_SIZE = 20;
 export const TerminalFontSize = Schema.Int.check(
@@ -136,6 +144,9 @@ export const ClientSettingsSchema = Schema.Struct({
   fontSizeCode: CodeFontSize.pipe(
     Schema.withDecodingDefault(Effect.succeed(DEFAULT_CODE_FONT_SIZE)),
   ),
+  fontSizeToolOutput: ToolOutputFontSize.pipe(
+    Schema.withDecodingDefault(Effect.succeed(DEFAULT_TOOL_OUTPUT_FONT_SIZE)),
+  ),
   fontSizeTerminal: TerminalFontSize.pipe(
     Schema.withDecodingDefault(Effect.succeed(DEFAULT_TERMINAL_FONT_SIZE)),
   ),
@@ -778,6 +789,7 @@ export const ClientSettingsPatch = Schema.Struct({
   fontSizeInterface: Schema.optionalKey(InterfaceFontSize),
   fontSizePrompt: Schema.optionalKey(PromptFontSize),
   fontSizeCode: Schema.optionalKey(CodeFontSize),
+  fontSizeToolOutput: Schema.optionalKey(ToolOutputFontSize),
   fontSizeTerminal: Schema.optionalKey(TerminalFontSize),
   fontFamilyCode: Schema.optionalKey(FontFamilyPreference),
   fontFamilyComposer: Schema.optionalKey(FontFamilyPreference),