Add back Uri ctor to HostedMcpServerTool

src/Libraries/.editorconfig

@@ -4533,7 +4533,7 @@ dotnet_diagnostic.S3994.severity = none
 # Title    : URI return values should not be strings
 # Category : Major Code Smell
 # Help Link: https://rules.sonarsource.com/csharp/RSPEC-3995
-dotnet_diagnostic.S3995.severity = warning
+dotnet_diagnostic.S3995.severity = suggestion
 
 # Title    : URI properties should not be strings
 # Category : Major Code Smell

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UriContent.cs

@@ -30,7 +30,7 @@ public class UriContent : AIContent
     /// <exception cref="ArgumentNullException"><paramref name="uri"/> is <see langword="null"/>.</exception>
     /// <exception cref="ArgumentNullException"><paramref name="mediaType"/> is <see langword="null"/>.</exception>
     /// <exception cref="ArgumentException"><paramref name="mediaType"/> is an invalid media type.</exception>
-    /// <exception cref="UriFormat"><paramref name="uri"/> is an invalid URL.</exception>
+    /// <exception cref="UriFormatException"><paramref name="uri"/> is an invalid URL.</exception>
     /// <remarks>
     /// A media type must be specified, so that consumers know what to do with the content.
     /// If an exact media type is not known, but the category (e.g. image) is known, a wildcard

src/Libraries/Microsoft.Extensions.AI.Abstractions/Tools/HostedMcpServerTool.cs

@@ -27,6 +27,31 @@ public HostedMcpServerTool(string serverName, string serverAddress)
         ServerAddress = Throw.IfNullOrWhitespace(serverAddress);
     }
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="HostedMcpServerTool"/> class.
+    /// </summary>
+    /// <param name="serverName">The name of the remote MCP server.</param>
+    /// <param name="serverUrl">The URL of the remote MCP server.</param>
+    /// <exception cref="ArgumentNullException"><paramref name="serverName"/> or <paramref name="serverUrl"/> is <see langword="null"/>.</exception>
+    /// <exception cref="ArgumentException"><paramref name="serverName"/> is empty or composed entirely of whitespace.</exception>
+    /// <exception cref="ArgumentException"><paramref name="serverUrl"/> is not an absolute URL.</exception>
+    public HostedMcpServerTool(string serverName, Uri serverUrl)
+        : this(serverName, ValidateUrl(serverUrl))
+    {
+    }
+
+    private static string ValidateUrl(Uri serverUrl)
+    {
+        _ = Throw.IfNull(serverUrl);
+
+        if (!serverUrl.IsAbsoluteUri)
+        {
+            Throw.ArgumentException(nameof(serverUrl), "The provided URL is not absolute.");
+        }
+
+        return serverUrl.AbsoluteUri;
+    }
+
     /// <inheritdoc />
     public override string Name => "mcp";
 

test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Tools/HostedMcpServerToolTests.cs

@@ -12,7 +12,7 @@ public class HostedMcpServerToolTests
     [Fact]
     public void Constructor_PropsDefault()
     {
-        HostedMcpServerTool tool = new("serverName", "https://localhost/");
+        HostedMcpServerTool tool = new("serverName", new Uri("https://localhost/"));
 
         Assert.Empty(tool.AdditionalProperties);
 
@@ -70,9 +70,14 @@ public void Constructor_Roundtrips()
     [Fact]
     public void Constructor_Throws()
     {
-        Assert.Throws<ArgumentException>(() => new HostedMcpServerTool(string.Empty, "https://localhost/"));
-        Assert.Throws<ArgumentNullException>(() => new HostedMcpServerTool(null!, "https://localhost/"));
-        Assert.Throws<ArgumentException>(() => new HostedMcpServerTool("name", string.Empty));
-        Assert.Throws<ArgumentNullException>(() => new HostedMcpServerTool("name", null!));
+        Assert.Throws<ArgumentException>("serverName", () => new HostedMcpServerTool(string.Empty, "https://localhost/"));
+        Assert.Throws<ArgumentException>("serverName", () => new HostedMcpServerTool(string.Empty, new Uri("https://localhost/")));
+        Assert.Throws<ArgumentNullException>("serverName", () => new HostedMcpServerTool(null!, "https://localhost/"));
+        Assert.Throws<ArgumentNullException>("serverName", () => new HostedMcpServerTool(null!, new Uri("https://localhost/")));
+
+        Assert.Throws<ArgumentException>("serverAddress", () => new HostedMcpServerTool("name", string.Empty));
+        Assert.Throws<ArgumentException>("serverUrl", () => new HostedMcpServerTool("name", new Uri("/api/mcp", UriKind.Relative)));
+        Assert.Throws<ArgumentNullException>("serverAddress", () => new HostedMcpServerTool("name", (string)null!));
+        Assert.Throws<ArgumentNullException>("serverUrl", () => new HostedMcpServerTool("name", (Uri)null!));
     }
 }

test/Libraries/Microsoft.Extensions.AI.OpenAI.Tests/OpenAIResponseClientIntegrationTests.cs

@@ -74,7 +74,7 @@ public async Task RemoteMCP_ListTools()
 
         ChatOptions chatOptions = new()
         {
-            Tools = [new HostedMcpServerTool("deepwiki", "https://mcp.deepwiki.com/mcp") { ApprovalMode = HostedMcpServerToolApprovalMode.NeverRequire }],
+            Tools = [new HostedMcpServerTool("deepwiki", new Uri("https://mcp.deepwiki.com/mcp")) { ApprovalMode = HostedMcpServerToolApprovalMode.NeverRequire }],
         };
 
         ChatResponse response = await CreateChatClient()!.GetResponseAsync("Which tools are available on the wiki_tools MCP server?", chatOptions);
@@ -96,7 +96,7 @@ async Task RunAsync(bool streaming, bool requireSpecific)
         {
             ChatOptions chatOptions = new()
             {
-                Tools = [new HostedMcpServerTool("deepwiki", "https://mcp.deepwiki.com/mcp")
+                Tools = [new HostedMcpServerTool("deepwiki", new Uri("https://mcp.deepwiki.com/mcp"))
                     {
                         ApprovalMode = requireSpecific ?
                             HostedMcpServerToolApprovalMode.RequireSpecific(null, ["read_wiki_structure", "ask_question"]) :
@@ -136,7 +136,7 @@ async Task RunAsync(bool streaming, bool requireSpecific, bool useConversationId
         {
             ChatOptions chatOptions = new()
             {
-                Tools = [new HostedMcpServerTool("deepwiki", "https://mcp.deepwiki.com/mcp")
+                Tools = [new HostedMcpServerTool("deepwiki", new Uri("https://mcp.deepwiki.com/mcp"))
                     {
                         ApprovalMode = requireSpecific ?
                             HostedMcpServerToolApprovalMode.RequireSpecific(["read_wiki_structure", "ask_question"], null) :

test/Libraries/Microsoft.Extensions.AI.OpenAI.Tests/OpenAIResponseClientTests.cs

@@ -929,7 +929,7 @@ public async Task McpToolCall_ApprovalRequired_NonStreaming(string role)
 
         var chatOptions = new ChatOptions
         {
-            Tools = [new HostedMcpServerTool("deepwiki", "https://mcp.deepwiki.com/mcp")]
+            Tools = [new HostedMcpServerTool("deepwiki", new Uri("https://mcp.deepwiki.com/mcp"))]
         };
         McpServerToolApprovalRequestContent approvalRequest;
 
@@ -1307,7 +1307,7 @@ public async Task McpToolCall_ApprovalNotRequired_NonStreaming(bool rawTool)
 
         AITool mcpTool = rawTool ?
             ResponseTool.CreateMcpTool("deepwiki", serverUri: new("https://mcp.deepwiki.com/mcp"), toolCallApprovalPolicy: new McpToolCallApprovalPolicy(GlobalMcpToolCallApprovalPolicy.NeverRequireApproval)).AsAITool() :
-            new HostedMcpServerTool("deepwiki", "https://mcp.deepwiki.com/mcp")
+            new HostedMcpServerTool("deepwiki", new Uri("https://mcp.deepwiki.com/mcp"))
             {
                 ApprovalMode = HostedMcpServerToolApprovalMode.NeverRequire,
             };
@@ -1723,7 +1723,7 @@ public async Task McpToolCall_ApprovalNotRequired_Streaming()
 
         ChatOptions chatOptions = new()
         {
-            Tools = [new HostedMcpServerTool("deepwiki", "https://mcp.deepwiki.com/mcp")
+            Tools = [new HostedMcpServerTool("deepwiki", new Uri("https://mcp.deepwiki.com/mcp"))
                 {
                     ApprovalMode = HostedMcpServerToolApprovalMode.NeverRequire,
                 }