What's Changed

• Remove s_additionalProperties from McpClientTool by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1080
• Migrate from Anthropic.SDK to official Anthropic package by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1083
• Improve caching in XmlToDescriptionGenerator by @stephentoub in https://github.com/modelcontextprotocol/csharp-sdk/pull/1010
• Support incremental scope consent (SEP-835) by @halter73 in https://github.com/modelcontextprotocol/csharp-sdk/pull/1084
• Resource subscribe should be true if handler provided by @PederHP in https://github.com/modelcontextprotocol/csharp-sdk/pull/676
• Add request duration to LogRequestHandlerCompleted and LogRequestHandlerException log messages by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1092
• Fix session timeout due to timestamp frequency mismatch and activity tracking by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1106
• Add CS1066 suppressor for MCP server methods with optional parameters by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1110
• Fix CreateSamplingHandler to use ChatRole.Tool for tool result messages by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1128
• Use fully-qualified type names in generated partial method signatures by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1135
• Optimize JsonRpcMessage deserialization with single-pass parsing by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1138
• Align telemetry with OpenTelemetry MCP semantic conventions by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1139

Documentation Updates

• Fix Icon.Theme documentation to match MCP specification by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1090
• Document HttpRequestException thrown by McpClient.CreateAsync by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1095
• Add missing exception documentation to public API surface by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1103
• Improve docs landing page by @gewarren in https://github.com/modelcontextprotocol/csharp-sdk/pull/1114
• Add CONTRIBUTING.md by @mikekistler in https://github.com/modelcontextprotocol/csharp-sdk/pull/1125

Repository Infrastructure Updates

• Update Microsoft.Extensions.AI dependencies to 10.1.0 by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1082
• Update Microsoft.Extensions.AI* packages to latest versions by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1093
• Remove private reflection from tests by @Copilot in https://github.com/modelcontextprotocol/csharp-sdk/pull/1107
• Bump actions/setup-node from 6.0.0 to 6.1.0 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1074
• Bump danielpalme/ReportGenerator-GitHub-Action from 5.5.0 to 5.5.1 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1073
• Bump actions/checkout from 5.0.1 to 6.0.0 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1005
• Bump version to 0.5.0-preview.2. Update NuGet Project URL. by @jeffhandley in https://github.com/modelcontextprotocol/csharp-sdk/pull/1078
• Bump actions/checkout from 6.0.0 to 6.0.1 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1100
• Bump becheran/mlc from 1.0.0 to 1.2.0 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1098
• Bump actions/upload-artifact from 5.0.0 to 6.0.0 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1099
• Bump actions/download-artifact from 6.0.0 to 7.0.0 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1097
• Bump the other-testing group with 1 update by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1101
• Bump Anthropic from 11.0.0 to 12.0.1 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1118
• Bump the other-testing group with 1 update by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1124
• Install mono in dev container by @mikekistler in https://github.com/modelcontextprotocol/csharp-sdk/pull/1133
• Add client conformance tests by @mikekistler in https://github.com/modelcontextprotocol/csharp-sdk/pull/1102
• Add examples of icons on tools, resources, prompts, and server implementation to EverythingServer by @mikekistler in https://github.com/modelcontextprotocol/csharp-sdk/pull/1096
• Bump version to 0.6.0-preview.1 by @jeffhandley in https://github.com/modelcontextprotocol/csharp-sdk/pull/1141
• Bump Anthropic from 12.0.1 to 12.1.0 by @dependabot[bot] in https://github.com/modelcontextprotocol/csharp-sdk/pull/1137

Full Changelog: https://github.com/modelcontextprotocol/csharp-sdk/compare/v0.5.0-preview.1...v0.6.0-preview.1