diff --git a/CHANGELOG.md b/CHANGELOG.md
index eae5c0167fa..cbd0b2012c1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -173,6 +173,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Agents/Google: clean tool JSON Schemas for `google-antigravity` the same as `google-gemini-cli` before Cloud Code Assist requests, preventing Claude tool calls from failing with `patternProperties` 400 errors. (#19860)
 - Tests/Telegram: add regression coverage for command-menu sync that asserts all `setMyCommands` entries are Telegram-safe and hyphen-normalized across native/custom/plugin command sources. (#19703) Thanks @obviyus.
 - Agents/Image: collapse resize diagnostics to one line per image and include visible pixel/byte size details in the log message for faster triage.
 - Auth/Cooldowns: clear all usage stats fields (`disabledUntil`, `disabledReason`, `failureCounts`) in `clearAuthProfileCooldown` so manual cooldown resets fully recover billing-disabled profiles without requiring direct file edits. (#19211) Thanks @nabbilkhan.
diff --git a/src/agents/pi-embedded-runner/google.e2e.test.ts b/src/agents/pi-embedded-runner/google.e2e.test.ts
index 30c8c7f8da6..f5e331b1428 100644
--- a/src/agents/pi-embedded-runner/google.e2e.test.ts
+++ b/src/agents/pi-embedded-runner/google.e2e.test.ts
@@ -33,4 +33,37 @@ describe("sanitizeToolsForGoogle", () => {
     expect(params.additionalProperties).toBeUndefined();
     expect(params.properties?.foo?.format).toBeUndefined();
   });
+
+  it("strips unsupported schema keywords for google-antigravity", () => {
+    const tool = {
+      name: "test",
+      description: "test",
+      parameters: {
+        type: "object",
+        patternProperties: {
+          "^x-": { type: "string" },
+        },
+        properties: {
+          foo: {
+            type: "string",
+            format: "uuid",
+          },
+        },
+      },
+      execute: async () => ({ ok: true, content: [] }),
+    } as unknown as AgentTool;
+
+    const [sanitized] = sanitizeToolsForGoogle({
+      tools: [tool],
+      provider: "google-antigravity",
+    });
+
+    const params = sanitized.parameters as {
+      patternProperties?: unknown;
+      properties?: Record<string, { format?: unknown }>;
+    };
+
+    expect(params.patternProperties).toBeUndefined();
+    expect(params.properties?.foo?.format).toBeUndefined();
+  });
 });
diff --git a/src/agents/pi-embedded-runner/google.ts b/src/agents/pi-embedded-runner/google.ts
index 07ad4a51895..7a6a0bf76cc 100644
--- a/src/agents/pi-embedded-runner/google.ts
+++ b/src/agents/pi-embedded-runner/google.ts
@@ -247,11 +247,11 @@ export function sanitizeToolsForGoogle<
   tools: AgentTool<TSchemaType, TResult>[];
   provider: string;
 }): AgentTool<TSchemaType, TResult>[] {
-  // google-antigravity serves Anthropic models (e.g. claude-opus-4-6-thinking),
-  // NOT Gemini. Applying Gemini schema cleaning strips JSON Schema keywords
-  // (minimum, maximum, format, etc.) that Anthropic's API requires for
-  // draft 2020-12 compliance. Only clean for actual Gemini providers.
-  if (params.provider !== "google-gemini-cli") {
+  // Cloud Code Assist uses the OpenAPI 3.03 `parameters` field for both Gemini
+  // AND Claude models.  This field does not support JSON Schema keywords such as
+  // patternProperties, additionalProperties, $ref, etc.  We must clean schemas
+  // for every provider that routes through this path.
+  if (params.provider !== "google-gemini-cli" && params.provider !== "google-antigravity") {
     return params.tools;
   }
   return params.tools.map((tool) => {