From 5c78bd7aa10fe89b1e09ed4cfad84028ae84ebc6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Beaufort?= <beaufort.francois@gmail.com>
Date: Wed, 12 Aug 2026 15:56:16 +0200
Subject: [PATCH 1/2] refactor: change RegisteredTool inputSchema type to
 object

---
 index.bs | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/index.bs b/index.bs
index 4274a31..32a299e 100644
--- a/index.bs
+++ b/index.bs
@@ -562,8 +562,9 @@ The <dfn method for=ModelContext>getTools(<var>options</var>)</dfn> method steps
             :: |tool definition|'s [=tool definition/description=]
 
             : {{RegisteredTool/inputSchema}}
-            :: |tool definition|'s [=tool definition/input schema=] if it is not the empty string;
-               otherwise undefined.
+            :: the result of [=parse a JSON string to a JavaScript value=] given |tool
+               definition|'s [=tool definition/input schema=], if |tool definition|'s [=tool
+               definition/input schema=] is not the empty string; otherwise undefined.
 
             : {{RegisteredTool/window}}
             :: |targetDocument|'s [=relevant global object=]
@@ -713,7 +714,7 @@ dictionary RegisteredTool {
   // done, and there's no need to do it again on tool exposure.
   DOMString title;
   required DOMString description;
-  DOMString inputSchema;
+  object inputSchema;
   required Window window;
   required USVString origin;
   ToolAnnotations annotations;
@@ -734,9 +735,9 @@ dictionary RegisteredTool {
      tool registration, via {{ModelContextTool/description}}.
 
   : <code><var ignore>tool</var>["{{RegisteredTool/inputSchema}}"]</code>
-  :: A stringified JSON Schema object describing the expected input parameters for the tool
-     [[!JSON-SCHEMA]]. It is the string derived from {{ModelContextTool/inputSchema}} during
-     registration.
+  :: A JSON Schema object describing the expected input parameters for the tool
+     [[!JSON-SCHEMA]]. It is the same value provided at tool registration, via
+     {{ModelContextTool/inputSchema}}.
 
   : <code><var ignore>tool</var>["{{RegisteredTool/window}}"]</code>
   :: The {{Window}} of the document that registered the tool.

From c1bbb5b76e2c1dcaf1b120c839159c84ca5c238c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Beaufort?= <beaufort.francois@gmail.com>
Date: Thu, 13 Aug 2026 08:27:59 +0200
Subject: [PATCH 2/2] Address feedback

---
 index.bs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/index.bs b/index.bs
index 32a299e..70b527f 100644
--- a/index.bs
+++ b/index.bs
@@ -566,6 +566,9 @@ The <dfn method for=ModelContext>getTools(<var>options</var>)</dfn> method steps
                definition|'s [=tool definition/input schema=], if |tool definition|'s [=tool
                definition/input schema=] is not the empty string; otherwise undefined.
 
+               Note: This will never throw an exception, because the string stored in the tool
+               definition is always a valid JSON string.
+
             : {{RegisteredTool/window}}
             :: |targetDocument|'s [=relevant global object=]
 
@@ -736,7 +739,7 @@ dictionary RegisteredTool {
 
   : <code><var ignore>tool</var>["{{RegisteredTool/inputSchema}}"]</code>
   :: A JSON Schema object describing the expected input parameters for the tool
-     [[!JSON-SCHEMA]]. It is the same value provided at tool registration, via
+     [[!JSON-SCHEMA]]. It is a deep copy of the schema provided at tool registration, via
      {{ModelContextTool/inputSchema}}.
 
   : <code><var ignore>tool</var>["{{RegisteredTool/window}}"]</code>