Use lowercase host in resource URI template derivation.

Author: eiriktsarpalis

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerResource.cs

@@ -264,7 +264,7 @@ private static AIFunctionFactoryOptions CreateAIFunctionFactoryOptions(
             Name = name,
             Title = options?.Title,
             Description = options?.Description,
-            MimeType = options?.MimeType,
+            MimeType = options?.MimeType ?? "application/octet-stream",
         };
 
         return new AIFunctionMcpServerResource(function, resource);
@@ -295,7 +295,7 @@ private static string DeriveUriTemplate(string name, AIFunction function)
     {
         StringBuilder template = new();
 
-        template.Append("resource://").Append(Uri.EscapeDataString(name));
+        template.Append("resource://").Append(Uri.EscapeDataString(name.ToLowerInvariant()));
 
         if (function.JsonSchema.TryGetProperty("properties", out JsonElement properties))
         {

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsResourcesTests.cs

@@ -268,8 +268,8 @@ public void Register_Resources_From_Current_Assembly()
         sc.AddMcpServer().WithResourcesFromAssembly();
         IServiceProvider services = sc.BuildServiceProvider();
 
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResource?.Uri == $"resource://{nameof(SimpleResources.SomeNeatDirectResource)}");
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://{nameof(SimpleResources.SomeNeatTemplatedResource)}{{?name}}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResource?.Uri == $"resource://{nameof(SimpleResources.SomeNeatDirectResource).ToLowerInvariant()}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://{nameof(SimpleResources.SomeNeatTemplatedResource).ToLowerInvariant()}{{?name}}");
     }
 
     [Fact]
@@ -279,13 +279,13 @@ public void Register_Resources_From_Multiple_Sources()
         sc.AddMcpServer()
             .WithResources<SimpleResources>()
             .WithResources<MoreResources>()
-            .WithResources([McpServerResource.Create(() => "42", new() { UriTemplate = "myResources://Returns42/{something}" })]);
+            .WithResources([McpServerResource.Create(() => "42", new() { UriTemplate = "myResources://returns42/{something}" })]);
         IServiceProvider services = sc.BuildServiceProvider();
 
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResource?.Uri == $"resource://{nameof(SimpleResources.SomeNeatDirectResource)}");
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://{nameof(SimpleResources.SomeNeatTemplatedResource)}{{?name}}");
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://{nameof(MoreResources.AnotherNeatDirectResource)}");
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate.UriTemplate == "myResources://Returns42/{something}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResource?.Uri == $"resource://{nameof(SimpleResources.SomeNeatDirectResource).ToLowerInvariant()}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://{nameof(SimpleResources.SomeNeatTemplatedResource).ToLowerInvariant()}{{?name}}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://{nameof(MoreResources.AnotherNeatDirectResource).ToLowerInvariant()}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate.UriTemplate == "myResources://returns42/{something}");
     }
 
     [McpServerResourceType]