Change default name casing of McpServerXx.Create tools/prompts

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerPrompt.cs

@@ -68,7 +68,7 @@ private static AIFunctionFactoryOptions CreateAIFunctionFactoryOptions(
         MethodInfo method, McpServerPromptCreateOptions? options) =>
         new()
         {
-            Name = options?.Name ?? method.GetCustomAttribute<McpServerPromptAttribute>()?.Name,
+            Name = options?.Name ?? method.GetCustomAttribute<McpServerPromptAttribute>()?.Name ?? AIFunctionMcpServerTool.DeriveName(method),
             Description = options?.Description,
             MarshalResult = static (result, _, cancellationToken) => new ValueTask<object?>(result),
             SerializerOptions = options?.SerializerOptions ?? McpJsonUtilities.DefaultOptions,

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerResource.cs

@@ -75,7 +75,7 @@ private static AIFunctionFactoryOptions CreateAIFunctionFactoryOptions(
         MethodInfo method, McpServerResourceCreateOptions? options) =>
         new()
         {
-            Name = options?.Name ?? method.GetCustomAttribute<McpServerResourceAttribute>()?.Name,
+            Name = options?.Name ?? method.GetCustomAttribute<McpServerResourceAttribute>()?.Name ?? AIFunctionMcpServerTool.DeriveName(method),
             Description = options?.Description,
             MarshalResult = static (result, _, cancellationToken) => new ValueTask<object?>(result),
             SerializerOptions = options?.SerializerOptions ?? McpJsonUtilities.DefaultOptions,

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerTool.cs

@@ -8,6 +8,7 @@
 using System.Reflection;
 using System.Text.Json;
 using System.Text.Json.Nodes;
+using System.Text.RegularExpressions;
 
 namespace ModelContextProtocol.Server;
 
@@ -74,7 +75,7 @@ private static AIFunctionFactoryOptions CreateAIFunctionFactoryOptions(
         MethodInfo method, McpServerToolCreateOptions? options) =>
         new()
         {
-            Name = options?.Name ?? method.GetCustomAttribute<McpServerToolAttribute>()?.Name,
+            Name = options?.Name ?? method.GetCustomAttribute<McpServerToolAttribute>()?.Name ?? DeriveName(method),
             Description = options?.Description,
             MarshalResult = static (result, _, cancellationToken) => new ValueTask<object?>(result),
             SerializerOptions = options?.SerializerOptions ?? McpJsonUtilities.DefaultOptions,
@@ -293,6 +294,63 @@ public override async ValueTask<CallToolResult> InvokeAsync(
         };
     }
 
+    /// <summary>Creates a name to use based on the supplied method and naming policy.</summary>
+    internal static string DeriveName(MethodInfo method, JsonNamingPolicy? policy = null)
+    {
+        string name = method.Name;
+
+        // Remove any "Async" suffix if the method is an async method and if the method name isn't just "Async".
+        const string AsyncSuffix = "Async";
+        if (IsAsyncMethod(method) &&
+            name.EndsWith(AsyncSuffix, StringComparison.Ordinal) &&
+            name.Length > AsyncSuffix.Length)
+        {
+            name = name.Substring(0, name.Length - AsyncSuffix.Length);
+        }
+
+        // Replace anything other than ASCII letters or digits with underscores, trim off any leading or trailing underscores.
+        name = NonAsciiLetterDigitsRegex().Replace(name, "_").Trim('_');
+
+        // If after all our transformations the name is empty, just use the original method name.
+        if (name.Length == 0)
+        {
+            name = method.Name;
+        }
+
+        // Case the name based on the provided naming policy.
+        return (policy ?? JsonNamingPolicy.SnakeCaseLower).ConvertName(name) ?? name;
+
+        static bool IsAsyncMethod(MethodInfo method)
+        {
+            Type t = method.ReturnType;
+
+            if (t == typeof(Task) || t == typeof(ValueTask))
+            {
+                return true;
+            }
+
+            if (t.IsGenericType)
+            {
+                t = t.GetGenericTypeDefinition();
+                if (t == typeof(Task<>) || t == typeof(ValueTask<>) || t == typeof(IAsyncEnumerable<>))
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+    }
+
+    /// <summary>Regex that flags runs of characters other than ASCII digits or letters.</summary>
+#if NET
+    [GeneratedRegex("[^0-9A-Za-z]+")]
+    private static partial Regex NonAsciiLetterDigitsRegex();
+#else
+    private static Regex NonAsciiLetterDigitsRegex() => _nonAsciiLetterDigits;
+    private static readonly Regex _nonAsciiLetterDigits = new("[^0-9A-Za-z]+", RegexOptions.Compiled);
+#endif
+
     private static JsonElement? CreateOutputSchema(AIFunction function, McpServerToolCreateOptions? toolCreateOptions, out bool structuredOutputRequiresWrapping)
     {
         structuredOutputRequiresWrapping = false;

tests/ModelContextProtocol.AspNetCore.Tests/MapMcpTests.cs

@@ -80,7 +80,7 @@ IHttpContextAccessor is not currently supported with non-stateless Streamable HT
         await using var mcpClient = await ConnectAsync();
 
         var response = await mcpClient.CallToolAsync(
-            "EchoWithUserName",
+            "echo_with_user_name",
             new Dictionary<string, object?>() { ["message"] = "Hello world!" },
             cancellationToken: TestContext.Current.CancellationToken);
 

tests/ModelContextProtocol.AspNetCore.Tests/SseIntegrationTests.cs

@@ -149,11 +149,11 @@ public async Task AddMcpServer_CanBeCalled_MultipleTimes()
         var tools = await mcpClient.ListToolsAsync(cancellationToken: TestContext.Current.CancellationToken);
 
         Assert.Equal(2, tools.Count);
-        Assert.Contains(tools, tools => tools.Name == "Echo");
+        Assert.Contains(tools, tools => tools.Name == "echo");
         Assert.Contains(tools, tools => tools.Name == "sampleLLM");
 
         var echoResponse = await mcpClient.CallToolAsync(
-            "Echo",
+            "echo",
             new Dictionary<string, object?>
             {
                 ["message"] = "from client!"

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsPromptsTests.cs

@@ -100,7 +100,7 @@ public async Task Can_List_And_Call_Registered_Prompts()
         var prompts = await client.ListPromptsAsync(TestContext.Current.CancellationToken);
         Assert.Equal(6, prompts.Count);
 
-        var prompt = prompts.First(t => t.Name == nameof(SimplePrompts.ReturnsChatMessages));
+        var prompt = prompts.First(t => t.Name == "returns_chat_messages");
         Assert.Equal("Returns chat messages", prompt.Description);
 
         var result = await prompt.GetAsync(new Dictionary<string, object?>() { ["message"] = "hello" }, cancellationToken: TestContext.Current.CancellationToken);
@@ -171,7 +171,7 @@ public async Task TitleAttributeProperty_PropagatedToTitle()
         Assert.NotNull(prompts);
         Assert.NotEmpty(prompts);
 
-        McpClientPrompt prompt = prompts.First(t => t.Name == nameof(SimplePrompts.ReturnsString));
+        McpClientPrompt prompt = prompts.First(t => t.Name == "returns_string");
 
         Assert.Equal("This is a title", prompt.Title);
     }
@@ -204,7 +204,7 @@ public async Task Throws_Exception_Missing_Parameter()
         await using IMcpClient client = await CreateMcpClientForServer();
 
         var e = await Assert.ThrowsAsync<McpException>(async () => await client.GetPromptAsync(
-            nameof(SimplePrompts.ReturnsChatMessages),
+            "returns_chat_messages",
             cancellationToken: TestContext.Current.CancellationToken));
 
         Assert.Equal(McpErrorCode.InternalError, e.ErrorCode);
@@ -242,7 +242,7 @@ public void Register_Prompts_From_Current_Assembly()
         sc.AddMcpServer().WithPromptsFromAssembly();
         IServiceProvider services = sc.BuildServiceProvider();
 
-        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(SimplePrompts.ReturnsChatMessages));
+        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == "returns_chat_messages");
     }
 
     [Fact]
@@ -255,10 +255,10 @@ public void Register_Prompts_From_Multiple_Sources()
             .WithPrompts([McpServerPrompt.Create(() => "42", new() { Name = "Returns42" })]);
         IServiceProvider services = sc.BuildServiceProvider();
 
-        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(SimplePrompts.ReturnsChatMessages));
-        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(SimplePrompts.ThrowsException));
-        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(SimplePrompts.ReturnsString));
-        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(MorePrompts.AnotherPrompt));
+        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == "returns_chat_messages");
+        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == "throws_exception");
+        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == "returns_string");
+        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == "another_prompt");
         Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == "Returns42");
     }
 

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsResourcesTests.cs

@@ -129,7 +129,7 @@ public async Task Can_List_And_Call_Registered_Resources()
         var resources = await client.ListResourcesAsync(TestContext.Current.CancellationToken);
         Assert.Equal(5, resources.Count);
 
-        var resource = resources.First(t => t.Name == nameof(SimpleResources.SomeNeatDirectResource));
+        var resource = resources.First(t => t.Name == "some_neat_direct_resource");
         Assert.Equal("Some neat direct resource", resource.Description);
 
         var result = await resource.ReadAsync(cancellationToken: TestContext.Current.CancellationToken);
@@ -146,7 +146,7 @@ public async Task Can_List_And_Call_Registered_ResourceTemplates()
         var resources = await client.ListResourceTemplatesAsync(TestContext.Current.CancellationToken);
         Assert.Equal(3, resources.Count);
 
-        var resource = resources.First(t => t.Name == nameof(SimpleResources.SomeNeatTemplatedResource));
+        var resource = resources.First(t => t.Name == "some_neat_templated_resource");
         Assert.Equal("Some neat resource with parameters", resource.Description);
 
         var result = await resource.ReadAsync(new Dictionary<string, object?>() { ["name"] = "hello" }, cancellationToken: TestContext.Current.CancellationToken);
@@ -204,13 +204,13 @@ public async Task TitleAttributeProperty_PropagatedToTitle()
         var resources = await client.ListResourcesAsync(cancellationToken: TestContext.Current.CancellationToken);
         Assert.NotNull(resources);
         Assert.NotEmpty(resources);
-        McpClientResource resource = resources.First(t => t.Name == nameof(SimpleResources.SomeNeatDirectResource));
+        McpClientResource resource = resources.First(t => t.Name == "some_neat_direct_resource");
         Assert.Equal("This is a title", resource.Title);
 
         var resourceTemplates = await client.ListResourceTemplatesAsync(cancellationToken: TestContext.Current.CancellationToken);
         Assert.NotNull(resourceTemplates);
         Assert.NotEmpty(resourceTemplates);
-        McpClientResourceTemplate resourceTemplate = resourceTemplates.First(t => t.Name == nameof(SimpleResources.SomeNeatTemplatedResource));
+        McpClientResourceTemplate resourceTemplate = resourceTemplates.First(t => t.Name == "some_neat_templated_resource");
         Assert.Equal("This is another title", resourceTemplate.Title);
     }
 
@@ -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://mcp/{nameof(SimpleResources.SomeNeatDirectResource)}");
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://mcp/{nameof(SimpleResources.SomeNeatTemplatedResource)}{{?name}}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResource?.Uri == $"resource://mcp/some_neat_direct_resource");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://mcp/some_neat_templated_resource{{?name}}");
     }
 
     [Fact]
@@ -282,9 +282,9 @@ public void Register_Resources_From_Multiple_Sources()
             .WithResources([McpServerResource.Create(() => "42", new() { UriTemplate = "myResources:///returns42/{something}" })]);
         IServiceProvider services = sc.BuildServiceProvider();
 
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResource?.Uri == $"resource://mcp/{nameof(SimpleResources.SomeNeatDirectResource)}");
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://mcp/{nameof(SimpleResources.SomeNeatTemplatedResource)}{{?name}}");
-        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://mcp/{nameof(MoreResources.AnotherNeatDirectResource)}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResource?.Uri == $"resource://mcp/some_neat_direct_resource");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://mcp/some_neat_templated_resource{{?name}}");
+        Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate?.UriTemplate == $"resource://mcp/another_neat_direct_resource");
         Assert.Contains(services.GetServices<McpServerResource>(), t => t.ProtocolResourceTemplate.UriTemplate == "myResources:///returns42/{something}");
     }