v0.1.0-preview.5

This release extends progress notification support, adds JsonSerializerOptions parameters for tool and prompt operations, adds initial OpenTelemetry observability, and reorganizes ASP.NET Core extension methods into the standard namespace.

Breaking Changes

Refer to the C# SDK Versioning documentation for details on versioning and breaking change policies.

1. Extend progress notification support #163
   • IMcpClient base interface changed to IMcpEndpoint
   • SamplingCapability.SamplingHandler delegate signature gained IProgress<ProgressNotificationValue> parameter
2. Put MapMcp in Microsoft.AspNetCore.Builder namespace #171
   • McpEndpointRouteBuilderExtensions moved from ModelContextProtocol.AspNetCore to Microsoft.AspNetCore.Builder namespace
3. Split StdioClient/ServerTransports into Stdio : Stream #172
   • StdioServerTransport stream-based constructor removed; base class changed from TransportBase to StreamServerTransport; StdioClientStreamTransport replaced by StdioClientSessionTransport and new StreamClientTransport
   • Migration: Use StreamServerTransport for custom stream-based servers; update StdioServerTransport constructor calls
4. Allow JsonSerializerOptions parameters #182
   • New JsonSerializerOptions? parameter inserted before cancellationToken in ListToolsAsync, EnumerateToolsAsync, GetPromptAsync
   • SendNotificationAsync extension method removed from McpClientExtensions
5. Remove McpServerConfig.Arguments property #192
   • McpServerConfig.Arguments property removed
   • Migration: Use McpServerConfig.TransportOptions["arguments"] instead

What's Changed

• Put MapMcp in Microsoft.AspNetCore.Builder namespace #171 by @halter73
• Split StdioClient/ServerTransports into Stdio : Stream #172 by @stephentoub
• Fixing WithPromptsFromAssembly #174 by @aaronpowell
• Enable IsAotCompatible for ModelContextProtocol.AspNetCore #175 by @stephentoub
• Configure hosted stdio servers to log to stderr #173 by @halter73
• Fix pagination handling in McpServer #177 by @stephentoub
• Extend progress notification support #163 by @Tyler-R-Kendrick (co-authored by @stephentoub)
• Make supposedly unreachable code less reachable #178 by @halter73
• Add initial Activity / Metric support #183 by @stephentoub
• Allow JsonSerializerOptions parameters for user-defined inputs and hardcode everything else to the source generator #182 by @eiriktsarpalis
• Write "event: message" to SSE response #192 by @halter73
• Changed the name of the ActivitySource and Metric to clarify that the semantic conventions have not been ratified yet #194 by @samsp-msft (co-authored by @stephentoub)
• Allow override of name and description of McpClientTool #165 by @PederHP
• Hardcode the source generator in one remaining location and simplify McpJsonUtilities #204 by @eiriktsarpalis
• Reduce dependencies to 8.x versions of packages #195 by @stephentoub
• Mark samples as AOT compatible #184 by @agocke (co-authored by @stephentoub)

Documentation Updates

• Fix AspNetCore README #170 by @halter73

Test Improvements

• Expand a few DI-related tests #201 by @stephentoub
• Add more unit tests #139 by @stvansolano (co-authored by @stephentoub)

Repository Infrastructure Updates

• Bump package version #169 by @eiriktsarpalis

Acknowledgements

• @Tyler-R-Kendrick made their first contribution in #163
• @agocke made their first contribution in #184
• @samsp-msft made their first contribution in #194
• @stvansolano made their first contribution in #139
• @zh6335901 submitted issue #154 (resolved by #165)
• @AArnott @JamesNK @lmolkova @WeihanLi reviewed pull requests

Full Changelog: v0.1.0-preview.4...v0.1.0-preview.5