diff --git a/packages/tool/src/index.ts b/packages/tool/src/index.ts
index 4078979..177a741 100644
--- a/packages/tool/src/index.ts
+++ b/packages/tool/src/index.ts
@@ -1,5 +1,5 @@
 import type { Tool, ToolExecuteOptions, ToolExecuteResult } from '@xsai/shared-chat'
-import type { Infer, InferIn, Schema } from 'xsschema'
+import type { Infer, InferIn, JsonSchema, Schema } from 'xsschema'
 
 import { toJsonSchema } from 'xsschema'
 
@@ -13,19 +13,25 @@ export interface ToolOptions<T1 extends Schema, T2 extends Schema | undefined =
   name: string
   parameters: T1
   returns?: T2
-  strict?: boolean
 }
 
 export interface ToolResult extends Tool {}
 
-export const tool = async <T1 extends Schema, T2 extends Schema | undefined = undefined>(options: ToolOptions<T1, T2>): Promise<ToolResult> => ({
-  execute: options.execute,
-  function: {
-    description: options.description,
-    name: options.name,
-    parameters: await toJsonSchema(options.parameters) as Record<string, unknown>,
-    returns: options.returns ? (await toJsonSchema(options.returns)) as Record<string, unknown> : undefined,
-    strict: options.strict,
-  },
-  type: 'function',
-})
+export const tool = async <T1 extends Schema, T2 extends Schema | undefined = undefined>(options: ToolOptions<T1, T2>): Promise<ToolResult> => {
+  const schema = await toJsonSchema(options.parameters)
+
+  return {
+    execute: options.execute,
+    function: {
+      description: options.description,
+      name: options.name,
+      parameters: {
+        ...schema,
+        additionalProperties: false,
+      } satisfies JsonSchema,
+      returns: options.returns ? (await toJsonSchema(options.returns)) as Record<string, unknown> : undefined,
+      strict: true,
+    },
+    type: 'function',
+  }
+}