From 1f7e1765a5e60443c7990136d8d093da6ba4e39c Mon Sep 17 00:00:00 2001
From: Tianyi Cui <53024+tianyicui@users.noreply.github.com>
Date: Wed, 22 Jul 2026 00:57:29 +0800
Subject: [PATCH] docs(tools): distinguish closed object validation

---
 packages/core/tools/README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/core/tools/README.md b/packages/core/tools/README.md
index 24588299d9..bc1f9ffeac 100644
--- a/packages/core/tools/README.md
+++ b/packages/core/tools/README.md
@@ -86,7 +86,7 @@ ctx.tools.register(defineTool({
 
 The unified schema DSL uses `ParameterSchemaSpec` for the implicit open parameter object and `ValueSchemaSpec` for any JSON-value root. It supports `string`, `number`, `integer`, `boolean`, `null`, `array`, `object`, author-only `json`, and exact-one `oneOf`; scalar `enum`/`const` values are type-correct. Every explicit DSL object declares `additionalProperties: true | false`, while the implicit parameter root and raw JSON Schema keep the standard open default.
 
-A `defineTool` definition validates model arguments before execution and turns missing required values, wrong primitives, invalid enum members, and nested violations into `ToolArgsError` (`INVALID_ARGS`) for the normal error-result path. Extra keys are allowed, defaults are not applied, and object or array fields without `properties` or `items` receive only a type check. Raw-registered tools own their validation.
+A `defineTool` definition validates model arguments before execution and turns missing required values, wrong primitives, invalid enum members, and nested violations into `ToolArgsError` (`INVALID_ARGS`) for the normal error-result path. The implicit parameter root is open; an explicit object accepts extra keys only with `additionalProperties: true`, and a closed object with no declared properties accepts only `{}`. Raw JSON Schema objects remain open unless they explicitly set `additionalProperties: false`. Defaults are not applied; open objects without `properties` and arrays without `items` receive only a container type check. Raw-registered tools own their validation.
 
 See `defineTool`, `validateArgs`, `ToolArgsError`, `ValueSchemaSpec`, `ParameterSchemaSpec`, `InferValue`, `InferArgs`, `valueSchemaSpecToJsonSchema`, and `parameterSchemaSpecToJsonSchema` in the public API for details.