From 7f4c44047904092f3e46e7039c5335c2675a8dfe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Beaufort?= <beaufort.francois@gmail.com>
Date: Tue, 9 Jun 2026 11:53:43 +0200
Subject: [PATCH 1/2] Reject registerTool promise if signal is aborted

---
 index.bs | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/index.bs b/index.bs
index f1bcd63..889ab4c 100644
--- a/index.bs
+++ b/index.bs
@@ -399,9 +399,8 @@ The <dfn method for=ModelContext>registerTool(<var>tool</var>, <var>options</var
 
 1. If |signal| [=map/exists=], then:
 
-   1. If |signal| is [=AbortSignal/aborted=], then optionally [=report a warning to the console=]
-      indicating that the tool was not registered because the {{AbortSignal}} was already
-      [=AbortSignal/aborted=], and return.
+   1. If |signal| is [=AbortSignal/aborted=], then return [=a promise rejected with=]
+      |signal|'s [=AbortSignal/abort reason=].
 
    1. [=AbortSignal/add|Add an abort algorithm=] to |signal| that [=model context/unregisters a
       tool=] given [=this=] and |tool name|.

From 8b465456a0e54b42c826c9aa16e22bc071750293 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Beaufort?= <beaufort.francois@gmail.com>
Date: Tue, 9 Jun 2026 13:31:19 +0200
Subject: [PATCH 2/2] Update abort algorithm

---
 index.bs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/index.bs b/index.bs
index 889ab4c..4189080 100644
--- a/index.bs
+++ b/index.bs
@@ -395,6 +395,8 @@ The <dfn method for=ModelContext>registerTool(<var>tool</var>, <var>options</var
 1. Let |untrusted content hint| be true if |tool|'s {{ModelContextTool/annotations}} [=map/exists=] and
    its {{ToolAnnotations/untrustedContentHint}} is true. Otherwise, let it be false.
 
+1. Let |promise| be [=a new promise=] created in [=this=]'s [=relevant realm=].
+
 1. Let |signal| be |options|'s {{ModelContextRegisterToolOptions/signal}}.
 
 1. If |signal| [=map/exists=], then:
@@ -402,8 +404,11 @@ The <dfn method for=ModelContext>registerTool(<var>tool</var>, <var>options</var
    1. If |signal| is [=AbortSignal/aborted=], then return [=a promise rejected with=]
       |signal|'s [=AbortSignal/abort reason=].
 
-   1. [=AbortSignal/add|Add an abort algorithm=] to |signal| that [=model context/unregisters a
-      tool=] given [=this=] and |tool name|.
+   1. [=AbortSignal/add|Add the following abort steps=] to |signal|:
+
+        1. [=model context/Unregister a tool=] given [=this=] and |tool name|.
+
+        1. [=Reject=] |promise| with |signal|'s [=AbortSignal/abort reason=].
 
 1. Let |exposed origins| be an empty [=list=] of [=origins=].
 
@@ -447,8 +452,6 @@ The <dfn method for=ModelContext>registerTool(<var>tool</var>, <var>options</var
 
 1. Set [=this=]'s [=ModelContext/internal context=][|tool name|] to |tool definition|.
 
-1. Let |promise| be [=a new promise=] created in [=this=]'s [=relevant realm=].
-
 1. Run the following steps [=in parallel=]:
 
   1. [=Notify documents of a tool change=] given |tool owner| and |exposed origins|.