csharp-sdk

## Breaking Changes The 0.5.0-preview.1 release includes several categories of breaking changes as we continue to refine the API surface area for the path toward a 1.0.0 stable release. Refer to the [C# SDK Versioning](https://modelcontextprotocol.github.io/csharp-sdk/versioning.html) documentation for information regarding our versioning, breaking change, and support approaches. 1. **[Add request options bag to high level requests and include Meta (#970)](https://github.com/modelcontextprotocol/csharp-sdk/pull/970)** * High-level request methods refactored to use options bag. Methods `CallToolAsync`, `GetPromptAsync`, `ListResourcesAsync`, `ReadResourceAsync`, `SubscribeResourceAsync`, `UnsubscribeResourceAsync`, `ListToolsAsync`, `ListPromptsAsync`, and similar now accept a new `RequestOptions` parameter instead of individual `JsonSerializerOptions` and `ProgressToken` parameters. * Code that passes `JsonSerializerOptions` or `ProgressToken` as named or positional parameters to high-level request methods will break and must be updated to use the `RequestOptions` bag instead. 2. **[Remove obsolete APIs from codebase (#985)](https://github.com/modelcontextprotocol/csharp-sdk/pull/985)** * `McpServerFactory` class: Removed obsolete factory class for creating MCP servers. * `McpClientFactory` class: Removed obsolete factory class for creating MCP clients. * Obsolete interfaces removed: `IMcpEndpoint`, `IMcpClient`, `IMcpServer` * Extension methods and properties that were previously marked obsolete are no longer available. * `LegacyTitledEnumSchema` and `EnumSchema` remain in place as obsolete APIs, but they now use a custom diagnostic ID of `MCP9001` instead of the default `CS0618` obsoletion diagnostic ID. This allows references to these APIs to be suppressed with a targeted diagnostic. 3. **[Fall back to well-known URL in client if 401 response is missing resource_metadata parameter (#1054)](https://github.com/modelcontextprotocol/csharp-sdk/pull/1054)** * `IsConfiguredEndpointRequest()` now properly validates absolute URIs by checking both host and scheme match, not just the path. This may cause previously accepted requests to be rejected if host/scheme don't match. * `ModelContextProtocol.AspNetCore.Authentication.McpAuthenticationOptions.ResourceMetadataUri` was changed from `string` to a nullable `string?`. * `ModelContextProtocol.Authentication.ProtectedResourceMetadata.Resource` was changed from `required Uri` to a non-required and nulalble `Uri?` 4. **[Remove McpClient.Enumerate*Async methods (#1060)](https://github.com/modelcontextprotocol/csharp-sdk/pull/1060)** * Removes `EnumerateToolsAsync`, `EnumeratePromptsAsync`, `EnumerateResourceTemplatesAsync`, and `EnumerateResourcesAsync` from the public API surface. These scenarios are covered by the corresponding `List*Async` methods. 5. **[Add McpClient/Session methods using .Protocol types (#1063)](https://github.com/modelcontextprotocol/csharp-sdk/pull/1063)** * Methods accepting a `CancellationToken token` had the argument renamed from `token` to `cancellationToken` for consistency throughout the SDK. * Methods accepting a `JsonSerializerOptions? serializerOptions` argument were updated to accept a `RequestOptions? options` argument instead, further adopting the `RequestOptions` class introduced in #970. * `ModelContextProtocol.Client.McpClient.CompleteAsync` was updated to add an optional `RequestOptions? options` argument, changing the position of the optional `CancellationToken` argument on the method signature. * `ModelContextProtocol.Client.McpClient.UnsubscribeFromResourceAsync` arguments were changed to now accept `UnsubscribeRequestParams requestParams, CancellationToken cancellationToken = default`. * `ModelContextProtocol.Client.McpClient.SetLoggingLevel` was renamed to `SetLoggingLevelAsync`. ## What's Changed * Add support for Client ID Metadata Documents to enable URL-based client registration by @MackinnonBuck in https://github.com/modelcontextprotocol/csharp-sdk/pull/1023 * MCP Core docs edit pass by @gewarren in https://github.com/modelcontextprotocol/csharp-sdk/pull/1033 * Adjust analyzer diagnostic severities and improve MCP001 reporting by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1038 * Remove obsolete APIs from codebase by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/985 * Add support for `data` to `McpProtocolException` by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1028 * Fix XML generator partial method issues by @jongalloway in https://github.com/modelcontextprotocol/csharp-sdk/pull/1059 * Remove McpClient.Enumerate*Async methods by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1060 * Add request options bag to high level requests and include Meta by @mikekistler in https://github.com/modelcontextprotocol/csharp-sdk/pull/970 * Add support for URL mode elicitation by @halter73 in https://github.com/modelcontextprotocol/csharp-sdk/pull/1021 * Synthesize return description into tool description when UseStructuredContent is false by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1049 * Add ResourceNotFound error code (-32002) by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1062 * Add McpClient/Session methods using .Protocol types by @stephentoub in https://github.com/modelcontextprotocol/csharp-sdk/pull/1063 * WithMeta for McpClientTool by @PederHP in https://github.com/modelcontextprotocol/csharp-sdk/pull/1027 * Fall back to well-known URL in client if 401 response is missing resource_metadata parameter by @halter73 in https://github.com/modelcontextprotocol/csharp-sdk/pull/1054 ## Documentation Updates * Core Protocol docs edit pass by @gewarren in https://github.com/modelcontextprotocol/csharp-sdk/pull/1032 * Docs edit pass (MCP.AspNetCore and a few other files) by @gewarren in https://github.com/modelcontextprotocol/csharp-sdk/pull/1034 * Update NuGet.org package owner to ModelContextProtocol by @jeffhandley https://github.com/modelcontextprotocol/csharp-sdk/pull/1071 ## Repository Infrastructure Updates * Add Conformance tests for the server by @mikekistler in https://github.com/modelcontextprotocol/csharp-sdk/pull/983 * Bump version to 0.5.0-preview.1 by @jeffhandley in https://github.com/modelcontextprotocol/csharp-sdk/pull/1035 * Bump the serilog-testing group with 1 update by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1046 * Bump actions/setup-dotnet from 5.0.0 to 5.0.1 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1045 * Bump the testing-frameworks group with 1 update by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1044 ## New Contributors * @jongalloway made their first contribution in https://github.com/modelcontextprotocol/csharp-sdk/pull/1059 **Full Changelog**: https://github.com/modelcontextprotocol/csharp-sdk/compare/v0.4.1-preview.1...v0.5.0-preview.1

csharp-sdk

v0.5.0-preview.1

Breaking Changes

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v0.5.0-preview.1

Breaking Changes

What's Changed

Documentation Updates

Repository Infrastructure Updates

New Contributors

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