v0.1.0-preview.13

This release adds McpServerResource, McpClientResource, and related resource template types, and updates the Microsoft.Extensions.AI dependency.

Breaking Changes

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

1. Resource type changes #391
   • ListResourcesAsync return type changed from IList<Resource> to IList<McpClientResource>
   • ListResourceTemplatesAsync return type changed similarly
   • ReadResourceRequestParams.Uri changed from optional to required
   • Multiple extension methods changed return types from Task<T> to ValueTask<T>
   • IMcpServerPrimitive.Name renamed to Id (resource names aren't unique)
   • McpServer now registers default handlers instead of failing for missing handlers

What's Changed

• Set IsError on CallToolResponse to true when result is ErrorContent #394 by @Astaggrock
• Add McpServer/ClientResource{Template} and friends #391 by @stephentoub
• Use WithResources in EverythingServer sample #400 by @stephentoub
• Update to latest M.E.AI version #401 by @stephentoub

Repository Infrastructure Updates

• Bump version to v0.1.0-preview.13 by @halter73

Acknowledgements

• @Astaggrock made their first contribution in #394
• @aaronpowell submitted #72 (resolved by #391)
• @Redth submitted #74 (resolved by #391)
• @halter73 @mikekistler reviewed pull requests

Full Changelog: v0.1.0-preview.12...v0.1.0-preview.13

v0.1.0-preview.12

This release adds client-side Streamable HTTP transport support, removes batching from StreamableHttpServerTransport, and introduces schema creation options for tools and prompts.

Breaking Changes

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

1. Removed batching support from StreamableHttpServerTransport #372
   • Server no longer accepts batched (JSON array) JSON-RPC requests on the Streamable HTTP transport

What's Changed

• Add SchemaCreateOptions in McpServerToolCreateOptions/McpServerPromptCreateOptions #354 by @1357310795
• Improve WeatherTools.GetAlerts description in sample #363 by @vladnega
• Add static resources to EverythingServer sample #361 by @mikekistler (co-authored by @halter73)
• Backfill trace injection test and migrate from request.params to request.params._meta #360 by @codefromthecrypt
• Add a McpClientTool.CallAsync helper #367 by @stephentoub
• Fix typo in McpSession.cs #371 by @stephentoub
• Update System and M.E.AI dependencies #374 by @stephentoub
• Add client-side Streamable HTTP transport support #356 by @halter73
• Remove batching support from StreamableHttpServerTransport #372 by @halter73

Repository Infrastructure Updates

• Bump version to v0.1.0-preview.12 by @halter73

Acknowledgements

• @1357310795 made their first contribution in #354
• @vladnega made their first contribution in #363
• @codefromthecrypt made their first contribution in #360
• @mikekistler made their first contribution in #361
• @mwiemer-microsoft submitted #370 (resolved by #371)
• @eiriktsarpalis @jeffhandley @lmolkova @samsp-msft reviewed pull requests

Full Changelog: v0.1.0-preview.11...v0.1.0-preview.12

v0.1.0-preview.11

The 0.1.0-preview.11 release fixes the SSE Server /message endpoint to use root-relative URIs, fixes GET accept header validation in the Streamable HTTP transport, and improves documentation.

What's Changed

• Emit root-relative /message endpoint when using SSE Server #323 by @dogdie233
• Fix GET accept header validation for server-side Streamable HTTP transport and improve testing #345 by @halter73

Documentation Updates

• Clarify McpClientTool inherits from AIFunction in README.md #338 by @ferrywlto (co-authored by @halter73)
• Fixed issue preventing README.md client example from compiling #346 by @PederHP

Repository Infrastructure Updates

• Bump version to v0.1.0-preview.11 #332 by @jeffhandley

Acknowledgements

• @dogdie233 made their first contribution in #323
• @ferrywlto made their first contribution in #338
• @eiriktsarpalis reviewed pull requests

Full Changelog: v0.1.0-preview.10...v0.1.0-preview.11

v0.1.0-preview.10

This release cleans up McpException and McpTransportException with the McpErrorCode enum, adds progress notification support for McpClientTool, and introduces server-side Streamable HTTP transport support.

Breaking Changes

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

1. Clean up McpException and McpTransportException (#321): McpException.ErrorCode changed from int? to McpErrorCode enum; McpTransportException class deleted; transport errors now throw InvalidOperationException

What's Changed

• Support progress notifications with McpClientTool and McpClientExtensions.CallToolAsync #312 by @stephentoub
• Add WithTools/Prompts overloads that accept McpServerTool/Prompts #319 by @stephentoub
• Clean up (use of) McpException and McpTransportException #321 by @stephentoub
• Add server-side Streamable HTTP transport support #330 by @halter73

Test Improvements

• Delete faulty assert #313 by @stephentoub
• Fix HandlesIProgressParameter test sporadically failing in CI #327 by @stephentoub

Repository Infrastructure Updates

• Bump version to 0.1.0-preview.10 #315 by @jeffhandley

Acknowledgements

• @LuisM000 @MaximPodolski @Meir017 @PederHP reviewed pull requests

Full Changelog: v0.1.0-preview.9...v0.1.0-preview.10

v0.1.0-preview.9

This release wraps each MCP request in a dependency injection service scope, introduces the Streamable HTTP transport with StreamableHttpHandler and WithHttpTransport, updates OpenTelemetry instrumentation with context propagation, and cleans up logging. It includes several breaking changes to handler delegate signatures, HTTP transport configuration, and transport base class APIs.

Breaking Changes

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

1. Wrap each request in a service scope #276

   • All capability handler delegate types changed from Func<..., Task<T>> to Func<..., ValueTask<T>> including SamplingHandler, ListToolsHandler, CallToolHandler, ListPromptsHandler, GetPromptHandler, and all resource/completion/logging handlers
   • McpServerTool.InvokeAsync and McpServerPrompt.GetAsync return types changed to ValueTask

2. Add StreamableHttpHandler and WithHttpTransport #291

   • MapMcp removed configureOptionsAsync and runSessionAsync parameters; configuration moved to WithHttpTransport(Action<HttpServerTransportOptions>?)
   • SseClientTransportOptions.MaxReconnectAttempts and ReconnectDelay properties removed

3. Clean up logging #286

   • TransportBase constructor changed from (ILoggerFactory?) to (string name, ILoggerFactory?) — required parameter added
   • TransportBase.EndpointName renamed to TransportBase.Name
   • TransportBase.Logger accessibility narrowed from protected to private protected
   • Custom transport implementations extending TransportBase must update

What's Changed

• Wrap each request in a service scope #276 by @stephentoub
• OpenTelemetry: context propagation and semconv update #262 by @lmolkova
• Add AdditionalHeader handling to ReceiveMessageAsync #295 by @ClosetheWorld
• Add StreamableHttpHandler and WithHttpTransport #291 by @halter73
• Remove unnecessary $ and fix some typos #305 by @MikeAlhayek
• Clean up logging #286 by @stephentoub

Documentation Updates

• Fix the docs and make them more readable #281 by @MikeAlhayek

Repository Infrastructure Updates

• Bump version to 0.1.0-preview.9 #284 by @eiriktsarpalis
• Workflow refactoring and improvements #273 by @jeffhandley

Acknowledgements

• @MikeAlhayek made their first contribution in #281
• @lmolkova made their first contribution in #262
• @ClosetheWorld made their first contribution in #295
• @JeffreySu submitted issue #234 (resolved by #276)
• @gong626035906 submitted issue #198 (resolved by #276)

Full Changelog: v0.1.0-preview.8...v0.1.0-preview.9

v0.1.0-preview.8

This release corrects the CreateMessageResult.Role type, exposes JsonSerializerOptions configuration across tool and prompt APIs, and adds comprehensive XML documentation comments across the SDK.

Breaking Changes

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

1. Fix CreateMessageResult.Role type #264
   • CreateMessageResult.Role changed from string to Role enum type
   • Migration: Replace string values like "assistant" with Role.Assistant or "user" with Role.User
2. Expose JsonSerializerOptions in prompts APIs #279
   • WithPrompts removed params modifier; added JsonSerializerOptions? serializerOptions parameter
   • Migration: Wrap multiple type arguments in a collection, e.g. WithPrompts([typeof(A), typeof(B)])
3. Expose JsonSerializerOptions in tools APIs #266
   • WithTools removed params modifier; added JsonSerializerOptions? serializerOptions parameter
   • Migration: Wrap multiple type arguments in a collection, e.g. WithTools([typeof(A), typeof(B)])

What's Changed

• Fix CreateMessageRule.Role to be of type Role #264 by @stephentoub
• Delete some dead methods from Log.cs #277 by @stephentoub
• Expose a JsonSerializerOptions setting in the prompts APIs #279 by @eiriktsarpalis

Documentation Updates

• Add XML documentation comments across the SDK #238 by @robch (co-authored by @stephentoub)
• Augment McpServerTool/Prompt docs with details of parameter/result marshaling #271 by @stephentoub

Test Improvements

• Disable STJ reflection for testing #266 by @eiriktsarpalis (co-authored by @stephentoub)

Repository Infrastructure Updates

• Bump version to 0.1.0-preview.8 #256 by @eiriktsarpalis

Acknowledgements

• @robch made their first contribution in #238
• @halter73 reviewed pull requests

Full Changelog: v0.1.0-preview.7...v0.1.0-preview.8

v0.1.0-preview.7

This release removes McpServerConfig in favor of McpClientOptions, introduces strong typing for request parameters, adds the server completions capability, enables notification handler registration after endpoint creation, and adds the Everything Server sample.

Breaking Changes

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

1. Allow notification handlers post-creation temporary registration #223
   • ClientCapabilities.NotificationHandlers and ServerCapabilities.NotificationHandlers delegate changed from Func<..., Task> to Func<..., CancellationToken, Task>
2. Use strong-typing of params in most remaining McpClientExtensions methods #224
   • CallToolRequestParams.Arguments changed from Dictionary<string, JsonElement>? to IReadOnlyDictionary<string, JsonElement>?
   • GetPromptRequestParams.Arguments similarly changed
3. Remove McpServerConfig and have McpClientFactory accept IClientTransport instances directly #230
   • McpServerConfig class deleted
   • McpClientFactory.CreateAsync parameter changed from McpServerConfig to IClientTransport
   • IClientTransport gained required Name property
4. Add server completions capability #232
   • GetCompletionAsync renamed to CompleteAsync
   • WithGetCompletionHandler renamed to WithCompleteHandler

What's Changed

• Fix api.weather.gov/points response handling in WeatherTools #134 by @stvansolano (co-authored by @halter73)
• Everything server #151 by @aaronpowell
• Fix and enhance cancellation operations across MCP Sessions #179 by @Tyler-R-Kendrick (co-authored by @stephentoub)
• Propagate fix from AIFunctionFactory to TemporaryAIFunctionFactory #215 by @stephentoub
• Allow notification handlers post-creation temporary registration #223 by @stephentoub
• Use strong-typing of params in most remaining McpClientExtensions methods #224 by @stephentoub
• Use Kestrel for all in-memory HTTP tests #225 by @halter73
• Stop the host when the single session server service finishes #226 by @stephentoub
• Enable servers to log to the clients via ILogger #229 by @stephentoub
• Remove McpServerConfig and have McpClientFactory accept IClientTransport instances directly #230 by @eiriktsarpalis (co-authored by @halter73)
• Add server completions capability #232 by @stephentoub
• Fix race in KestrelInMemoryConnection #233 by @halter73
• Fix StdioServerTransport.DisposeAsync hang #235 by @halter73
• Update M.E.AI to latest version #241 by @stephentoub
• Avoid propagating server tool exception message to client #242 by @stephentoub
• Fixes #248 - Add CultureInfo.InvariantCulture to string interpolation #249 by @DGuhr
• Improve SSE response handling and URI construction in SseClientSession #251 by @239573049
• Use TryAddEnumerable for McpServerOptionsSetup #252 by @halter73
• Fix race in TransportBase.SetConnected #253 by @halter73
• Separate ASP.NET Core tests into a distinct project and make the main test project netfx compatible #254 by @eiriktsarpalis (co-authored by @halter73)

Documentation Updates

• Add SECURITY.md #239 by @jeffhandley

Repository Infrastructure Updates

• Bump package version to 0.1.0-preview.7 #212 by @eiriktsarpalis
• Bump xunit.v3 to 2.0.0 #231 by @eiriktsarpalis
• Update markdown-link-check to ignore external links causing 403 in CI #246 by @jeffhandley

Acknowledgements

• @DGuhr made their first contribution in #249
• @239573049 made their first contribution in #251
• @chuckries submitted #214 (resolved by #215)
• @StefH submitted #155 (resolved by #226)
• @mbcrawfo submitted #221 (resolved by #235)
• @dsp-ant @PederHP @tripathi-gaurav reviewed pull requests

Full Changelog: v0.1.0-preview.6...v0.1.0-preview.7

v0.1.0-preview.6

This release consolidates exception types into McpException and moves notification handler registrations into the capabilities model.

Breaking Changes

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

1. Consolidate McpClientException/McpServerException into McpException #209
   • McpClientException class deleted
   • IMcpClient.ServerCapabilities changed from nullable to non-nullable (throws InvalidOperationException if not connected); same for ServerInfo
2. Move notification handler registrations to capabilities #207
   • AddNotificationHandler removed from IMcpEndpoint
   • Notification handlers now set via ClientCapabilities.NotificationHandlers and ServerCapabilities.NotificationHandlers

What's Changed

• Disable response buffering for SSE responses #208 by @halter73
• Consolidate McpClientException/McpServerException into McpException #209 by @stephentoub
• Move notification handler registrations to capabilities #207 by @stephentoub

Repository Infrastructure Updates

• Bump package version to 0.1.0-preview.6 #206 by @eiriktsarpalis

Acknowledgements

• @PederHP @Youssef1313 reviewed pull requests

Full Changelog: v0.1.0-preview.5...v0.1.0-preview.6

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

v0.1.0-preview.4

This release introduces the ModelContextProtocol.AspNetCore package for hosting MCP servers in ASP.NET Core applications with SSE transport support.

Breaking Changes

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

1. Add ModelContextProtocol.AspNetCore #160
   • HttpListenerSseServerTransport removed
   • IServerTransport interface removed
   • MapMcpSse renamed to MapMcp and moved to the new ModelContextProtocol.AspNetCore package

What's Changed

• Add ModelContextProtocol.AspNetCore #160 by @halter73 (co-authored by @eiriktsarpalis @jeffhandley)

Repository Infrastructure Updates

• Bump package version #167 by @eiriktsarpalis

Acknowledgements

• @stephentoub reviewed pull requests

Full Changelog: v0.1.0-preview.3...v0.1.0-preview.4