diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/CHANGELOG.md b/src/Libraries/Microsoft.Extensions.AI.Abstractions/CHANGELOG.md
index 34c83f701c1..37ffe79f892 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/CHANGELOG.md
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Added non-invocable `AIFunctionDeclaration` (base class for `AIFunction`), `AIFunctionFactory.CreateDeclaration`, and `AIFunction.AsDeclarationOnly`.
 - Added `[Experimental]` support for user approval of function invocations via `ApprovalRequiredAIFunction`, `FunctionApprovalRequestContent`, and friends.
+- Added `[Experimental]` support for MCP server-hosted tools via `HostedMcpServerTool`, `HostedMcpServerToolApprovalMode`, and friends.
 
 ## 9.8.0
 
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/HostedMcpServerToolRequireSpecificApprovalMode.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/HostedMcpServerToolRequireSpecificApprovalMode.cs
index a5e870af7e7..42a39f35c50 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/HostedMcpServerToolRequireSpecificApprovalMode.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/HostedMcpServerToolRequireSpecificApprovalMode.cs
@@ -6,6 +6,9 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 
+#pragma warning disable S109 // Magic numbers should not be used
+#pragma warning disable EA0011 // Consider removing unnecessary conditional access operator (?)
+
 namespace Microsoft.Extensions.AI;
 
 /// <summary>
@@ -42,7 +45,7 @@ public override bool Equals(object? obj) => obj is HostedMcpServerToolRequireSpe
 
     /// <inheritdoc/>
     public override int GetHashCode() =>
-        HashCode.Combine(GetListHashCode(AlwaysRequireApprovalToolNames), GetListHashCode(NeverRequireApprovalToolNames));
+        Combine(GetListHashCode(AlwaysRequireApprovalToolNames), GetListHashCode(NeverRequireApprovalToolNames));
 
     private static bool ListEquals(IList<string>? list1, IList<string>? list2) =>
         ReferenceEquals(list1, list2) ||
@@ -55,12 +58,32 @@ private static int GetListHashCode(IList<string>? list)
             return 0;
         }
 
+#if NET
         HashCode hc = default;
-        foreach (string item in list)
+        for (int i = 0; i < list.Count; i++)
         {
-            hc.Add(item);
+            hc.Add(list[i]);
         }
 
         return hc.ToHashCode();
+#else
+        int hash = 0;
+        for (int i = 0; i < list.Count; i++)
+        {
+            hash = Combine(hash, list[i]?.GetHashCode() ?? 0);
+        }
+
+        return hash;
+#endif
+    }
+
+    private static int Combine(int h1, int h2)
+    {
+#if NET
+        return HashCode.Combine(h1, h2);
+#else
+        uint rol5 = ((uint)h1 << 5) | ((uint)h1 >> 27);
+        return ((int)rol5 + h1) ^ h2;
+#endif
     }
 }
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.csproj b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.csproj
index 25aa2f4c49d..f5472854def 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.csproj
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.csproj
@@ -32,7 +32,6 @@
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
     <PackageReference Include="System.Text.Json" />
-    <PackageReference Include="Microsoft.Bcl.HashCode" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net462'">
diff --git a/src/Libraries/Microsoft.Extensions.AI.OpenAI/CHANGELOG.md b/src/Libraries/Microsoft.Extensions.AI.OpenAI/CHANGELOG.md
index 15859a5744d..ded1e85533f 100644
--- a/src/Libraries/Microsoft.Extensions.AI.OpenAI/CHANGELOG.md
+++ b/src/Libraries/Microsoft.Extensions.AI.OpenAI/CHANGELOG.md
@@ -2,9 +2,9 @@
 
 ## NOT YET RELEASED
 
+- Updated to depend on OpenAI 2.4.0
 - Updated tool mappings to recognize any `AIFunctionDeclaration`.
 - Updated to accommodate the additions in `Microsoft.Extensions.AI.Abstractions`.
-- Updated to depend on OpenAI 2.4.0
 
 ## 9.8.0-preview.1.25412.6
 
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/HostedMcpServerToolApprovalModeTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/HostedMcpServerToolApprovalModeTests.cs
index 3ad4690130a..9f72a194f06 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/HostedMcpServerToolApprovalModeTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/HostedMcpServerToolApprovalModeTests.cs
@@ -45,4 +45,51 @@ public void Serialization_RequireSpecific_Roundtrips()
         HostedMcpServerToolApprovalMode? result = JsonSerializer.Deserialize(json, TestJsonSerializerContext.Default.HostedMcpServerToolApprovalMode);
         Assert.Equal(requireSpecific, result);
     }
+
+    [Fact]
+    public void Equality_RequireSpecific_WorksAsExpected()
+    {
+        var mode1 = HostedMcpServerToolApprovalMode.RequireSpecific(["ToolA", "ToolB"], ["ToolC"]);
+        var mode2 = HostedMcpServerToolApprovalMode.RequireSpecific(["ToolA", "ToolB"], ["ToolC"]);
+        Assert.Equal(mode1, mode2);
+        Assert.Equal(mode1.GetHashCode(), mode2.GetHashCode());
+
+        Assert.NotNull(mode1.AlwaysRequireApprovalToolNames);
+        mode1.AlwaysRequireApprovalToolNames.Add("ToolD");
+        Assert.NotEqual(mode1, mode2);
+        Assert.NotEqual(mode1.GetHashCode(), mode2.GetHashCode());
+
+        Assert.NotNull(mode2.AlwaysRequireApprovalToolNames);
+        mode2.AlwaysRequireApprovalToolNames.Add("ToolD");
+        Assert.Equal(mode1, mode2);
+        Assert.Equal(mode1.GetHashCode(), mode2.GetHashCode());
+
+        Assert.NotNull(mode2.NeverRequireApprovalToolNames);
+        mode2.NeverRequireApprovalToolNames.Add("ToolE");
+        Assert.NotEqual(mode1, mode2);
+        Assert.NotEqual(mode1.GetHashCode(), mode2.GetHashCode());
+
+        Assert.NotNull(mode1.NeverRequireApprovalToolNames);
+        mode1.NeverRequireApprovalToolNames.Add("ToolE");
+        Assert.Equal(mode1, mode2);
+        Assert.Equal(mode1.GetHashCode(), mode2.GetHashCode());
+
+        var mode3 = HostedMcpServerToolApprovalMode.RequireSpecific(null, null);
+        Assert.Equal(mode3.GetHashCode(), mode3.GetHashCode());
+        var mode4 = HostedMcpServerToolApprovalMode.RequireSpecific(["a"], null);
+        Assert.Equal(mode4.GetHashCode(), mode4.GetHashCode());
+        Assert.NotEqual(mode3, mode4);
+        Assert.NotEqual(mode3.GetHashCode(), mode4.GetHashCode());
+
+        var mode5 = HostedMcpServerToolApprovalMode.RequireSpecific(null, ["b"]);
+        Assert.Equal(mode5.GetHashCode(), mode5.GetHashCode());
+        Assert.NotEqual(mode3, mode5);
+        Assert.NotEqual(mode3.GetHashCode(), mode5.GetHashCode());
+        Assert.NotEqual(mode4, mode5);
+        Assert.NotEqual(mode4.GetHashCode(), mode5.GetHashCode());
+
+        var mode6 = HostedMcpServerToolApprovalMode.RequireSpecific([], []);
+        Assert.Equal(mode6.GetHashCode(), mode6.GetHashCode());
+        Assert.NotEqual(mode3, mode6);
+    }
 }