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Add [McpServerTool] support for instance methods (#100)

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* Add [McpServerTool] support for instance methods

By popular demand, enables [McpServerTool] on instance methods. The instance is constructed per invocation, using ActivatorUtilities.CreateInstance when possible so that constructor arguments are satisfied from DI.

* Add disposal tests
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Stephen Toub 2025-03-26 09:34:30 -04:00 • committed by GitHub
commit b61cdef994
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1 changed files with 391 additions and 38 deletions
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59
src/ModelContextProtocol/Configuration/McpServerBuilderExtensions.Tools.cs
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@ -14,32 +14,51 @@ public static partial class McpServerBuilderExtensions
{
private const string RequiresUnreferencedCodeMessage = "This method requires dynamic lookup of method metadata and might not work in Native AOT.";
/// <summary>
/// Adds a tool to the server.
/// </summary>
/// <summary>Adds <see cref="McpServerTool"/> instances to the service collection backing <paramref name="builder"/>.</summary>
/// <typeparam name="TTool">The tool type.</typeparam>
/// <param name="builder">The builder instance.</param>
/// <exception cref="ArgumentNullException"><paramref name="builder"/> is <see langword="null"/>.</exception>
public static IMcpServerBuilder WithTools<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods)] TTool>(
/// <remarks>
/// This method discovers all instance and static methods (public and non-public) on the specified <typeparamref name="TTool"/>
/// type, where the methods are attributed as <see cref="McpServerToolAttribute"/>, and adds an <see cref="McpServerTool"/>
/// instance for each. For instance methods, an instance will be constructed for each invocation of the tool.
/// </remarks>
public static IMcpServerBuilder WithTools<[DynamicallyAccessedMembers(
DynamicallyAccessedMemberTypes.PublicMethods |
DynamicallyAccessedMemberTypes.NonPublicMethods |
DynamicallyAccessedMemberTypes.PublicConstructors)] TTool>(
this IMcpServerBuilder builder)
{
Throw.IfNull(builder);
foreach (var toolMethod in GetToolMethods(typeof(TTool)))
foreach (var toolMethod in typeof(TTool).GetMethods(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance))
{
builder.Services.AddSingleton(services => McpServerTool.Create(toolMethod, services: services));
if (toolMethod.GetCustomAttribute<McpServerToolAttribute>() is not null)
{
if (toolMethod.IsStatic)
{
builder.Services.AddSingleton(services => McpServerTool.Create(toolMethod, services: services));
}
else
{
builder.Services.AddSingleton(services => McpServerTool.Create(toolMethod, typeof(TTool), services: services));
}
}
}
return builder;
}
/// <summary>
/// Adds tools to the server.
/// </summary>
/// <summary>Adds <see cref="McpServerTool"/> instances to the service collection backing <paramref name="builder"/>.</summary>
/// <param name="builder">The builder instance.</param>
/// <param name="toolTypes">Types with marked methods to add as tools to the server.</param>
/// <exception cref="ArgumentNullException"><paramref name="builder"/> is <see langword="null"/>.</exception>
/// <exception cref="ArgumentNullException"><paramref name="toolTypes"/> is <see langword="null"/>.</exception>
/// <remarks>
/// This method discovers all instance and static methods (public and non-public) on the specified <paramref name="toolTypes"/>
/// types, where the methods are attributed as <see cref="McpServerToolAttribute"/>, and adds an <see cref="McpServerTool"/>
/// instance for each. For instance methods, an instance will be constructed for each invocation of the tool.
/// </remarks>
[RequiresUnreferencedCode(RequiresUnreferencedCodeMessage)]
public static IMcpServerBuilder WithTools(this IMcpServerBuilder builder, params IEnumerable<Type> toolTypes)
{
@ -50,13 +69,23 @@ public static partial class McpServerBuilderExtensions
{
if (toolType is not null)
{
foreach (var toolMethod in GetToolMethods(toolType))
foreach (var method in toolType.GetMethods(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance))
{
builder.Services.AddSingleton(services => McpServerTool.Create(toolMethod, services: services));
if (method.GetCustomAttribute<McpServerToolAttribute>() is not null)
{
if (method.IsStatic)
{
builder.Services.AddSingleton(services => McpServerTool.Create(method, services: services));
}
else
{
builder.Services.AddSingleton(services => McpServerTool.Create(method, toolType, services: services));
}
}
}
}
}
return builder;
}
@ -78,10 +107,4 @@ public static partial class McpServerBuilderExtensions
where t.GetCustomAttribute<McpServerToolTypeAttribute>() is not null
select t);
}
private static IEnumerable<MethodInfo> GetToolMethods(
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods)] Type toolType) =>
from method in toolType.GetMethods(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static)
where method.GetCustomAttribute<McpServerToolAttribute>() is not null
select method;
}