diff --git a/src/agents/pi-embedded-runner/google.ts b/src/agents/pi-embedded-runner/google.ts
index 868db5983ed..fb7b968e765 100644
--- a/src/agents/pi-embedded-runner/google.ts
+++ b/src/agents/pi-embedded-runner/google.ts
@@ -245,7 +245,11 @@ export function sanitizeToolsForGoogle<
   tools: AgentTool<TSchemaType, TResult>[];
   provider: string;
 }): AgentTool<TSchemaType, TResult>[] {
-  if (params.provider !== "google-antigravity" && params.provider !== "google-gemini-cli") {
+  // 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") {
     return params.tools;
   }
   return params.tools.map((tool) => {