diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Functions/AIFunctionFactory.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Functions/AIFunctionFactory.cs
index e864923883e..5ad178e7bc8 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Functions/AIFunctionFactory.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Functions/AIFunctionFactory.cs
@@ -1058,8 +1058,7 @@ private record struct DescriptorKey(
            ( null   # null literal
            | false  # false literal
            | true   # true literal
-           | \d     # positive number
-           | -\d    # negative number
+           | -?[0-9]# number
            | "      # string
            | \[     # start array
            | {      # start object
diff --git a/test/Libraries/Microsoft.Extensions.AI.Tests/Functions/AIFunctionFactoryTest.cs b/test/Libraries/Microsoft.Extensions.AI.Tests/Functions/AIFunctionFactoryTest.cs
index b15d200a39a..afced22038f 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Tests/Functions/AIFunctionFactoryTest.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Tests/Functions/AIFunctionFactoryTest.cs
@@ -103,10 +103,13 @@ public async Task Parameters_ToleratesJsonEncodedParameters()
     [InlineData("  \"I am a string!\" ")]
     [InlineData("  {}")]
     [InlineData("[]")]
+    [InlineData("// single-line comment\r\nnull")]
+    [InlineData("/* multi-line\r\ncomment */\r\nnull")]
     public async Task Parameters_ToleratesJsonStringParameters(string jsonStringParam)
     {
-        AIFunction func = AIFunctionFactory.Create((JsonElement param) => param);
-        JsonElement expectedResult = JsonDocument.Parse(jsonStringParam).RootElement;
+        JsonSerializerOptions options = new(AIJsonUtilities.DefaultOptions) { ReadCommentHandling = JsonCommentHandling.Skip };
+        AIFunction func = AIFunctionFactory.Create((JsonElement param) => param, serializerOptions: options);
+        JsonElement expectedResult = JsonDocument.Parse(jsonStringParam, new() { CommentHandling = JsonCommentHandling.Skip }).RootElement;
 
         var result = await func.InvokeAsync(new()
         {