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Add middleware and authz support for server-side handlers (#733)

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Stephen Halter 2025-09-10 10:07:45 -07:00 • committed by GitHub
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1 changed files with 2871 additions and 435 deletions
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74
src/ModelContextProtocol.Core/Server/AIFunctionMcpServerTool.cs
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@ -1,7 +1,5 @@
using Microsoft.Extensions.AI;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using ModelContextProtocol.Protocol;
using System.ComponentModel;
using System.Diagnostics;
@ -15,8 +13,8 @@ namespace ModelContextProtocol.Server;
/// <summary>Provides an <see cref="McpServerTool"/> that's implemented via an <see cref="AIFunction"/>.</summary>
internal sealed partial class AIFunctionMcpServerTool : McpServerTool
{
private readonly ILogger _logger;
private readonly bool _structuredOutputRequiresWrapping;
private readonly IReadOnlyList<object> _metadata;
/// <summary>
/// Creates an <see cref="McpServerTool"/> instance for a method, specified via a <see cref="Delegate"/> instance.
@ -26,7 +24,7 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
McpServerToolCreateOptions? options)
{
Throw.IfNull(method);
options = DeriveOptions(method.Method, options);
return Create(method.Method, method.Target, options);
@ -146,7 +144,7 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
}
}
return new AIFunctionMcpServerTool(function, tool, options?.Services, structuredOutputRequiresWrapping);
return new AIFunctionMcpServerTool(function, tool, options?.Services, structuredOutputRequiresWrapping, options?.Metadata ?? []);
}
private static McpServerToolCreateOptions DeriveOptions(MethodInfo method, McpServerToolCreateOptions? options)
@ -186,6 +184,9 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
newOptions.Description ??= descAttr.Description;
}
// Set metadata if not already provided
newOptions.Metadata ??= CreateMetadata(method);
return newOptions;
}
@ -193,17 +194,22 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
internal AIFunction AIFunction { get; }
/// <summary>Initializes a new instance of the <see cref="McpServerTool"/> class.</summary>
private AIFunctionMcpServerTool(AIFunction function, Tool tool, IServiceProvider? serviceProvider, bool structuredOutputRequiresWrapping)
private AIFunctionMcpServerTool(AIFunction function, Tool tool, IServiceProvider? serviceProvider, bool structuredOutputRequiresWrapping, IReadOnlyList<object> metadata)
{
AIFunction = function;
ProtocolTool = tool;
_logger = serviceProvider?.GetService<ILoggerFactory>()?.CreateLogger<McpServerTool>() ?? (ILogger)NullLogger.Instance;
ProtocolTool.McpServerTool = this;
_structuredOutputRequiresWrapping = structuredOutputRequiresWrapping;
_metadata = metadata;
}
/// <inheritdoc />
public override Tool ProtocolTool { get; }
/// <inheritdoc />
public override IReadOnlyList<object> Metadata => _metadata;
/// <inheritdoc />
public override async ValueTask<CallToolResult> InvokeAsync(
RequestContext<CallToolRequestParams> request, CancellationToken cancellationToken = default)
@ -211,7 +217,7 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
Throw.IfNull(request);
cancellationToken.ThrowIfCancellationRequested();
request.Services = new RequestServiceProvider<CallToolRequestParams>(request, request.Services);
request.Services = new RequestServiceProvider<CallToolRequestParams>(request);
AIFunctionArguments arguments = new() { Services = request.Services };
if (request.Params?.Arguments is { } argDict)
@ -223,24 +229,7 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
}
object? result;
try
{
result = await AIFunction.InvokeAsync(arguments, cancellationToken).ConfigureAwait(false);
}
catch (Exception e) when (e is not OperationCanceledException)
{
ToolCallError(request.Params?.Name ?? string.Empty, e);
string errorMessage = e is McpException ?
$"An error occurred invoking '{request.Params?.Name}': {e.Message}" :
$"An error occurred invoking '{request.Params?.Name}'.";
return new()
{
IsError = true,
Content = [new TextContentBlock { Text = errorMessage }],
};
}
result = await AIFunction.InvokeAsync(arguments, cancellationToken).ConfigureAwait(false);
JsonNode? structuredContent = CreateStructuredResponse(result);
return result switch
@ -257,27 +246,27 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
Content = [],
StructuredContent = structuredContent,
},
string text => new()
{
Content = [new TextContentBlock { Text = text }],
StructuredContent = structuredContent,
},
ContentBlock content => new()
{
Content = [content],
StructuredContent = structuredContent,
},
IEnumerable<AIContent> contentItems => ConvertAIContentEnumerableToCallToolResult(contentItems, structuredContent),
IEnumerable<ContentBlock> contents => new()
{
Content = [.. contents],
StructuredContent = structuredContent,
},
CallToolResult callToolResponse => callToolResponse,
_ => new()
@ -336,6 +325,26 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
}
}
/// <summary>Creates metadata from attributes on the specified method and its declaring class, with the MethodInfo as the first item.</summary>
internal static IReadOnlyList<object> CreateMetadata(MethodInfo method)
{
// Add the MethodInfo to the start of the metadata similar to what RouteEndpointDataSource does for minimal endpoints.
List<object> metadata = [method];
// Add class-level attributes first, since those are less specific.
if (method.DeclaringType is not null)
{
metadata.AddRange(method.DeclaringType.GetCustomAttributes());
}
// Add method-level attributes second, since those are more specific.
// When metadata conflicts, later metadata usually takes precedence with exceptions for metadata like
// IAllowAnonymous which always take precedence over IAuthorizeData no matter the order.
metadata.AddRange(method.GetCustomAttributes());
return metadata.AsReadOnly();
}
/// <summary>Regex that flags runs of characters other than ASCII digits or letters.</summary>
#if NET
[GeneratedRegex("[^0-9A-Za-z]+")]
@ -446,7 +455,4 @@ internal sealed partial class AIFunctionMcpServerTool : McpServerTool
IsError = allErrorContent && hasAny
};
}
[LoggerMessage(Level = LogLevel.Error, Message = "\"{ToolName}\" threw an unhandled exception.")]
private partial void ToolCallError(string toolName, Exception exception);
}