diff --git a/extensions/minimax/speech-provider.test.ts b/extensions/minimax/speech-provider.test.ts
index a30f9e9d20a..5bf102d1526 100644
--- a/extensions/minimax/speech-provider.test.ts
+++ b/extensions/minimax/speech-provider.test.ts
@@ -449,6 +449,32 @@ describe("buildMinimaxSpeechProvider", () => {
       expect(voiceSetting.pitch).toBe(0);
     });
 
+    it("drops malformed voice settings before synthesis", async () => {
+      const hexAudio = Buffer.from("audio").toString("hex");
+      const mockFetch = vi.mocked(globalThis.fetch);
+      mockFetch.mockResolvedValueOnce(
+        new Response(JSON.stringify({ data: { audio: hexAudio } }), { status: 200 }),
+      );
+
+      await provider.synthesize({
+        text: "Test",
+        cfg: {} as never,
+        providerConfig: {
+          apiKey: "sk-test",
+          speed: 3,
+          vol: -1,
+          pitch: 20,
+        },
+        target: "audio-file",
+        timeoutMs: 30000,
+      });
+
+      const voiceSetting = firstFetchBody().voice_setting as Record<string, unknown>;
+      expect(voiceSetting.speed).toBe(1);
+      expect(voiceSetting.vol).toBe(1);
+      expect(voiceSetting.pitch).toBe(0);
+    });
+
     it("uses a MiniMax Token Plan env var when no API key is configured", async () => {
       process.env.MINIMAX_CODING_API_KEY = "sk-cp-env";
       const hexAudio = Buffer.from("audio").toString("hex");
diff --git a/extensions/minimax/speech-provider.ts b/extensions/minimax/speech-provider.ts
index 7483d9cbcdc..9d27901284f 100644
--- a/extensions/minimax/speech-provider.ts
+++ b/extensions/minimax/speech-provider.ts
@@ -11,7 +11,8 @@ import type {
   SpeechProviderOverrides,
   SpeechProviderPlugin,
 } from "openclaw/plugin-sdk/speech-core";
-import { asFiniteNumber, asObject, trimToUndefined } from "openclaw/plugin-sdk/speech-core";
+import { asObject, trimToUndefined } from "openclaw/plugin-sdk/speech-core";
+import { asFiniteNumberInRange } from "openclaw/plugin-sdk/string-coerce-runtime";
 import {
   DEFAULT_MINIMAX_TTS_BASE_URL,
   MINIMAX_TTS_MODELS,
@@ -108,12 +109,25 @@ function normalizeMinimaxProviderConfig(
       trimToUndefined(raw?.voiceId) ??
       trimToUndefined(process.env.MINIMAX_TTS_VOICE_ID) ??
       "English_expressive_narrator",
-    speed: asFiniteNumber(raw?.speed),
-    vol: asFiniteNumber(raw?.vol),
-    pitch: asFiniteNumber(raw?.pitch),
+    speed: normalizeMinimaxSpeed(raw?.speed),
+    vol: normalizeMinimaxVolume(raw?.vol),
+    pitch: normalizeMinimaxPitch(raw?.pitch),
   };
 }
 
+function normalizeMinimaxSpeed(value: unknown): number | undefined {
+  return asFiniteNumberInRange(value, { min: 0.5, max: 2 });
+}
+
+function normalizeMinimaxVolume(value: unknown): number | undefined {
+  return asFiniteNumberInRange(value, { min: 0, max: 10, minExclusive: true });
+}
+
+function normalizeMinimaxPitch(value: unknown): number | undefined {
+  const pitch = asFiniteNumberInRange(value, { min: -12, max: 12 });
+  return pitch !== undefined ? Math.trunc(pitch) : undefined;
+}
+
 function readMinimaxProviderConfig(
   config: SpeechProviderConfig,
   cfg?: OpenClawConfig,
@@ -124,9 +138,9 @@ function readMinimaxProviderConfig(
     baseUrl: normalizeMinimaxTtsBaseUrl(trimToUndefined(config.baseUrl) ?? normalized.baseUrl),
     model: trimToUndefined(config.model) ?? normalized.model,
     voiceId: trimToUndefined(config.voiceId) ?? normalized.voiceId,
-    speed: asFiniteNumber(config.speed) ?? normalized.speed,
-    vol: asFiniteNumber(config.vol) ?? normalized.vol,
-    pitch: asFiniteNumber(config.pitch) ?? normalized.pitch,
+    speed: normalizeMinimaxSpeed(config.speed) ?? normalized.speed,
+    vol: normalizeMinimaxVolume(config.vol) ?? normalized.vol,
+    pitch: normalizeMinimaxPitch(config.pitch) ?? normalized.pitch,
   };
 }
 
@@ -139,9 +153,9 @@ function readMinimaxOverrides(
   return {
     model: trimToUndefined(overrides.model),
     voiceId: trimToUndefined(overrides.voiceId),
-    speed: asFiniteNumber(overrides.speed),
-    vol: asFiniteNumber(overrides.vol),
-    pitch: asFiniteNumber(overrides.pitch),
+    speed: normalizeMinimaxSpeed(overrides.speed),
+    vol: normalizeMinimaxVolume(overrides.vol),
+    pitch: normalizeMinimaxPitch(overrides.pitch),
   };
 }
 
@@ -236,15 +250,15 @@ export function buildMinimaxSpeechProvider(): SpeechProviderPlugin {
         ...(trimToUndefined(talkProviderConfig.voiceId) == null
           ? {}
           : { voiceId: trimToUndefined(talkProviderConfig.voiceId) }),
-        ...(asFiniteNumber(talkProviderConfig.speed) == null
+        ...(normalizeMinimaxSpeed(talkProviderConfig.speed) == null
           ? {}
-          : { speed: asFiniteNumber(talkProviderConfig.speed) }),
-        ...(asFiniteNumber(talkProviderConfig.vol) == null
+          : { speed: normalizeMinimaxSpeed(talkProviderConfig.speed) }),
+        ...(normalizeMinimaxVolume(talkProviderConfig.vol) == null
           ? {}
-          : { vol: asFiniteNumber(talkProviderConfig.vol) }),
-        ...(asFiniteNumber(talkProviderConfig.pitch) == null
+          : { vol: normalizeMinimaxVolume(talkProviderConfig.vol) }),
+        ...(normalizeMinimaxPitch(talkProviderConfig.pitch) == null
           ? {}
-          : { pitch: asFiniteNumber(talkProviderConfig.pitch) }),
+          : { pitch: normalizeMinimaxPitch(talkProviderConfig.pitch) }),
       };
     },
     resolveTalkOverrides: ({ params }) => ({
@@ -254,9 +268,15 @@ export function buildMinimaxSpeechProvider(): SpeechProviderPlugin {
       ...(trimToUndefined(params.modelId) == null
         ? {}
         : { model: trimToUndefined(params.modelId) }),
-      ...(asFiniteNumber(params.speed) == null ? {} : { speed: asFiniteNumber(params.speed) }),
-      ...(asFiniteNumber(params.vol) == null ? {} : { vol: asFiniteNumber(params.vol) }),
-      ...(asFiniteNumber(params.pitch) == null ? {} : { pitch: asFiniteNumber(params.pitch) }),
+      ...(normalizeMinimaxSpeed(params.speed) == null
+        ? {}
+        : { speed: normalizeMinimaxSpeed(params.speed) }),
+      ...(normalizeMinimaxVolume(params.vol) == null
+        ? {}
+        : { vol: normalizeMinimaxVolume(params.vol) }),
+      ...(normalizeMinimaxPitch(params.pitch) == null
+        ? {}
+        : { pitch: normalizeMinimaxPitch(params.pitch) }),
     }),
     listVoices: async () => MINIMAX_TTS_VOICES.map((voice) => ({ id: voice, name: voice })),
     isConfigured: ({ cfg, providerConfig }) =>
diff --git a/src/plugin-sdk/string-coerce-runtime.ts b/src/plugin-sdk/string-coerce-runtime.ts
index 8aae2968b30..98a4490a5e9 100644
--- a/src/plugin-sdk/string-coerce-runtime.ts
+++ b/src/plugin-sdk/string-coerce-runtime.ts
@@ -15,6 +15,7 @@ export {
   readStringValue,
 } from "../shared/string-coerce.js";
 export {
+  asFiniteNumberInRange,
   asFiniteNumber,
   asPositiveSafeInteger,
   parseFiniteNumber,
diff --git a/src/shared/number-coercion.test.ts b/src/shared/number-coercion.test.ts
index 7526fc9b4d5..2cb90b85229 100644
--- a/src/shared/number-coercion.test.ts
+++ b/src/shared/number-coercion.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, test } from "vitest";
-import { asFiniteNumber, parseFiniteNumber } from "./number-coercion.js";
+import { asFiniteNumber, asFiniteNumberInRange, parseFiniteNumber } from "./number-coercion.js";
 
 describe("number-coercion", () => {
   test("asFiniteNumber accepts only finite numbers", () => {
@@ -9,6 +9,14 @@ describe("number-coercion", () => {
     expect(asFiniteNumber(Number.POSITIVE_INFINITY)).toBeUndefined();
   });
 
+  test("asFiniteNumberInRange enforces inclusive and exclusive bounds", () => {
+    expect(asFiniteNumberInRange(0.5, { min: 0.5, max: 2 })).toBe(0.5);
+    expect(asFiniteNumberInRange(2, { min: 0.5, max: 2 })).toBe(2);
+    expect(asFiniteNumberInRange(0.5, { min: 0.5, minExclusive: true })).toBeUndefined();
+    expect(asFiniteNumberInRange(10, { max: 10, maxExclusive: true })).toBeUndefined();
+    expect(asFiniteNumberInRange("1", { min: 0, max: 2 })).toBeUndefined();
+  });
+
   test("parseFiniteNumber accepts finite numbers and numeric strings", () => {
     expect(parseFiniteNumber(4)).toBe(4);
     expect(parseFiniteNumber("4.5")).toBe(4.5);
diff --git a/src/shared/number-coercion.ts b/src/shared/number-coercion.ts
index f8a36f6b3a7..abeb059d5e8 100644
--- a/src/shared/number-coercion.ts
+++ b/src/shared/number-coercion.ts
@@ -2,6 +2,32 @@ export function asFiniteNumber(value: unknown): number | undefined {
   return typeof value === "number" && Number.isFinite(value) ? value : undefined;
 }
 
+export function asFiniteNumberInRange(
+  value: unknown,
+  range: {
+    min?: number;
+    max?: number;
+    minExclusive?: boolean;
+    maxExclusive?: boolean;
+  },
+): number | undefined {
+  const number = asFiniteNumber(value);
+  if (number === undefined) {
+    return undefined;
+  }
+  if (range.min !== undefined) {
+    if (range.minExclusive ? number <= range.min : number < range.min) {
+      return undefined;
+    }
+  }
+  if (range.max !== undefined) {
+    if (range.maxExclusive ? number >= range.max : number > range.max) {
+      return undefined;
+    }
+  }
+  return number;
+}
+
 export function parseFiniteNumber(value: unknown): number | undefined {
   if (typeof value === "number") {
     return Number.isFinite(value) ? value : undefined;