The MCP C# SDK is the official .NET implementation of the Model Context Protocol, the open protocol that standardizes how applications supply context, data sources, and tools to large language models. It lets .NET applications, services, and libraries act as MCP clients, MCP servers, or both.
The SDK ships as several NuGet packages so a project takes only what it needs. A core package carries the client and low-level server APIs with minimal dependencies. The main package adds hosting and dependency injection extensions and suits most projects that do not serve HTTP. An ASP.NET Core package builds HTTP-based MCP servers.
Two extension packages cover newer parts of the protocol: MCP Apps, for interactive UI applications that render inside MCP hosts, and MCP Tasks, for running long tool invocations asynchronously with status polling and input requests. The SDK also supports the Identity Assertion Authorization Grant flow for cross-application access in enterprise-managed authorization.
Features
- Client and server APIs: implement MCP clients and servers from any .NET application, service, or library
- Core package: client and low-level server APIs with the minimum number of dependencies
- Hosting and dependency injection: the main package integrates with .NET hosting and DI
- ASP.NET Core servers: a dedicated package for HTTP-based MCP servers
- MCP Apps extension: build interactive UI applications that render inside MCP hosts
- MCP Tasks extension: run long tool calls asynchronously with status polling and input requests
- Cross-application access: support for the Identity Assertion Authorization Grant flow
