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jeffhandley merged 2 commits into from
Feb 24, 2026
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Remove MCP9002 obsolete APIs and document obsolete diagnostics #1366

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Copilot Feb 24, 2026
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Remove APIs marked as Obsolete with MCP9002
Copilot Feb 24, 2026
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13 changes: 12 additions & 1 deletion docs/list-of-diagnostics.md
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Expand Up @@ -23,4 +23,15 @@ If you use experimental APIs, you will get one of the diagnostics shown below. T

| Diagnostic ID | Description |
| :------------ | :---------- |
| `MCPEXP001` | MCP experimental APIs including Tasks and Extensions. Tasks provide a mechanism for asynchronous long-running operations that can be polled for status and results (see [MCP Tasks specification](https://modelcontextprotocol.io/specification/draft/basic/utilities/tasks)). Extensions provide a framework for extending the Model Context Protocol while maintaining interoperability (see [SEP-2133](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2133)). |
| `MCPEXP001` | MCP experimental APIs including Tasks and Extensions. Tasks provide a mechanism for asynchronous long-running operations that can be polled for status and results (see [MCP Tasks specification](https://modelcontextprotocol.io/specification/draft/basic/utilities/tasks)). Extensions provide a framework for extending the Model Context Protocol while maintaining interoperability (see [SEP-2133](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2133)). |

## Obsolete APIs

Obsolete diagnostic IDs are in the format `MCP9###`.

When APIs are marked as obsolete, a diagnostic is emitted to warn users that the API will be removed in a future version. Diagnostic IDs are never reused, even after an obsolete API has been removed, to avoid suppressing warnings for different APIs.

| Diagnostic ID | Status | Description |
| :------------ | :----- | :---------- |
| `MCP9001` | In place | The `EnumSchema` and `LegacyTitledEnumSchema` APIs are deprecated as of specification version 2025-11-25. Use the current schema APIs instead. |
| `MCP9002` | Removed | The `AddXxxFilter` extension methods on `IMcpServerBuilder` (e.g., `AddListToolsFilter`, `AddCallToolFilter`, `AddIncomingMessageFilter`) were superseded by `WithRequestFilters()` and `WithMessageFilters()`. |
6 changes: 2 additions & 4 deletions src/Common/Obsoletions.cs
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Expand Up @@ -23,8 +23,6 @@ internal static class Obsoletions
public const string LegacyTitledEnumSchema_Message = "The EnumSchema and LegacyTitledEnumSchema APIs are deprecated as of specification version 2025-11-25 and will be removed in a future major version. See SEP-1330 for more information.";
public const string LegacyTitledEnumSchema_Url = "https://github.com/modelcontextprotocol/modelcontextprotocol/issues/1330";

public const string MessageAndRequestFilter_DiagnosticId = "MCP9002";
public const string MessageAndRequestFilter_Url = "https://github.com/modelcontextprotocol/csharp-sdk/pull/1308";
public const string MessageFilter_Message = "Use WithMessageFilters() instead.";
public const string RequestFilter_Message = "Use WithRequestFilters() instead.";
// MCP9002 was used for the AddXxxFilter extension methods on IMcpServerBuilder that were superseded by
// WithMessageFilters() and WithRequestFilters(). The APIs were removed; do not reuse this diagnostic ID.
}
133 changes: 0 additions & 133 deletions src/ModelContextProtocol/McpServerBuilderExtensions.cs
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Expand Up @@ -925,139 +925,6 @@ public static IMcpServerBuilder WithRequestFilters(this IMcpServerBuilder builde
return builder;
}

#pragma warning disable CS0436 // ObsoleteAttribute polyfill conflicts with framework type on netstandard.

/// <summary>
/// Adds a filter to the list resource templates handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddListResourceTemplatesFilter(this IMcpServerBuilder builder, McpRequestFilter<ListResourceTemplatesRequestParams, ListResourceTemplatesResult> filter) =>
builder.WithRequestFilters(filters => filters.AddListResourceTemplatesFilter(filter));

/// <summary>
/// Adds a filter to the list tools handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddListToolsFilter(this IMcpServerBuilder builder, McpRequestFilter<ListToolsRequestParams, ListToolsResult> filter) =>
builder.WithRequestFilters(filters => filters.AddListToolsFilter(filter));

/// <summary>
/// Adds a filter to the call tool handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddCallToolFilter(this IMcpServerBuilder builder, McpRequestFilter<CallToolRequestParams, CallToolResult> filter) =>
builder.WithRequestFilters(filters => filters.AddCallToolFilter(filter));

/// <summary>
/// Adds a filter to the list prompts handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddListPromptsFilter(this IMcpServerBuilder builder, McpRequestFilter<ListPromptsRequestParams, ListPromptsResult> filter) =>
builder.WithRequestFilters(filters => filters.AddListPromptsFilter(filter));

/// <summary>
/// Adds a filter to the get prompt handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddGetPromptFilter(this IMcpServerBuilder builder, McpRequestFilter<GetPromptRequestParams, GetPromptResult> filter) =>
builder.WithRequestFilters(filters => filters.AddGetPromptFilter(filter));

/// <summary>
/// Adds a filter to the list resources handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddListResourcesFilter(this IMcpServerBuilder builder, McpRequestFilter<ListResourcesRequestParams, ListResourcesResult> filter) =>
builder.WithRequestFilters(filters => filters.AddListResourcesFilter(filter));

/// <summary>
/// Adds a filter to the read resource handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddReadResourceFilter(this IMcpServerBuilder builder, McpRequestFilter<ReadResourceRequestParams, ReadResourceResult> filter) =>
builder.WithRequestFilters(filters => filters.AddReadResourceFilter(filter));

/// <summary>
/// Adds a filter to the complete handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddCompleteFilter(this IMcpServerBuilder builder, McpRequestFilter<CompleteRequestParams, CompleteResult> filter) =>
builder.WithRequestFilters(filters => filters.AddCompleteFilter(filter));

/// <summary>
/// Adds a filter to the subscribe-to-resources handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddSubscribeToResourcesFilter(this IMcpServerBuilder builder, McpRequestFilter<SubscribeRequestParams, EmptyResult> filter) =>
builder.WithRequestFilters(filters => filters.AddSubscribeToResourcesFilter(filter));

/// <summary>
/// Adds a filter to the unsubscribe-from-resources handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddUnsubscribeFromResourcesFilter(this IMcpServerBuilder builder, McpRequestFilter<UnsubscribeRequestParams, EmptyResult> filter) =>
builder.WithRequestFilters(filters => filters.AddUnsubscribeFromResourcesFilter(filter));

/// <summary>
/// Adds a filter to the set logging level handler pipeline.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.RequestFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddSetLoggingLevelFilter(this IMcpServerBuilder builder, McpRequestFilter<SetLevelRequestParams, EmptyResult> filter) =>
builder.WithRequestFilters(filters => filters.AddSetLoggingLevelFilter(filter));

/// <summary>
/// Adds a filter to intercept all incoming JSON-RPC messages.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the message handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.MessageFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddIncomingMessageFilter(this IMcpServerBuilder builder, McpMessageFilter filter) =>
builder.WithMessageFilters(filters => filters.AddIncomingFilter(filter));

/// <summary>
/// Adds a filter to intercept all outgoing JSON-RPC messages.
/// </summary>
/// <param name="builder">The builder instance.</param>
/// <param name="filter">The filter function that wraps the message handler.</param>
/// <returns>The builder provided in <paramref name="builder"/>.</returns>
[Obsolete(Obsoletions.MessageFilter_Message, DiagnosticId = Obsoletions.MessageAndRequestFilter_DiagnosticId, UrlFormat = Obsoletions.MessageAndRequestFilter_Url)]
public static IMcpServerBuilder AddOutgoingMessageFilter(this IMcpServerBuilder builder, McpMessageFilter filter) =>
builder.WithMessageFilters(filters => filters.AddOutgoingFilter(filter));

#pragma warning restore CS0436
#endregion

#region Transports
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