Support Zod v3 and v4.

Author: kalenkevich

core/package.json

@@ -43,7 +43,7 @@
     "@modelcontextprotocol/sdk": "^1.24.0",
     "google-auth-library": "^10.3.0",
     "lodash-es": "^4.17.22",
-    "zod": "3.25.76"
+    "zod": "^4.2.1"
   },
   "devDependencies": {
     "@types/lodash-es": "^4.17.12",

core/src/tools/function_tool.ts

@@ -4,35 +4,33 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {FunctionDeclaration, Schema, Type} from '@google/genai';
-import {
-  type infer as zInfer,
-  ZodObject,
-  type ZodRawShape,
-} from 'zod';
+import { FunctionDeclaration, Schema, Type } from '@google/genai';
+import { z as z3 } from 'zod/v3';
+import { z as z4 } from 'zod/v4';
 
-import {isZodObject, zodObjectToSchema} from '../utils/simple_zod_to_json.js';
+import { isZodObject, zodObjectToSchema } from '../utils/simple_zod_to_json.js';
 
-import {BaseTool, RunAsyncToolRequest} from './base_tool.js';
-import {ToolContext} from './tool_context.js';
+import { BaseTool, RunAsyncToolRequest } from './base_tool.js';
+import { ToolContext } from './tool_context.js';
 
 /**
  * Input parameters of the function tool.
  */
-export type ToolInputParameters =
-  | undefined
-  | ZodObject<ZodRawShape>
-  | Schema;
+export type ToolInputParameters = | undefined | z3.ZodObject<z3.ZodRawShape> | z4.ZodObject | Schema;
+
+type ZodObject<T extends Record<string, any>> = z3.ZodObject<z3.ZodRawShape> | z4.ZodObject<T>;
 
 /*
  * The arguments of the function tool.
  */
 export type ToolExecuteArgument<TParameters extends ToolInputParameters> =
-  TParameters extends ZodObject<infer T, infer U, infer V>
-    ? zInfer<ZodObject<T, U, V>>
-    : TParameters extends Schema
-      ? unknown
-      : string;
+  TParameters extends z3.ZodObject<infer T, infer U, infer V>
+  ? z3.infer<z3.ZodObject<T, U, V>>
+  : TParameters extends z4.ZodObject<infer T>
+  ? z4.infer<z4.ZodObject<T>>
+  : TParameters extends Schema
+  ? unknown
+  : string;
 
 /*
  * The function to execute by the tool.
@@ -65,7 +63,7 @@ export type ToolOptions<
 function toSchema<TParameters extends ToolInputParameters>(
   parameters: TParameters): Schema {
   if (parameters === undefined) {
-    return {type: Type.OBJECT, properties: {}};
+    return { type: Type.OBJECT, properties: {} };
   }
 
   if (isZodObject(parameters)) {
@@ -120,7 +118,7 @@ export class FunctionTool<
   override async runAsync(req: RunAsyncToolRequest): Promise<unknown> {
     try {
       let validatedArgs: unknown = req.args;
-      if (this.parameters instanceof ZodObject) {
+      if (isZodObject(this.parameters)) {
         validatedArgs = this.parameters.parse(req.args);
       }
       return await this.execute(

core/src/utils/gemini_schema_util.ts

@@ -9,7 +9,7 @@ import {z} from 'zod';
 
 const MCPToolSchema = z.object({
   type: z.literal('object'),
-  properties: z.record(z.unknown()).optional(),
+  properties: z.record(z.string(), z.unknown()).optional(),
   required: z.string().array().optional(),
 });
 type MCPToolSchema = z.infer<typeof MCPToolSchema>;