json-rpc 2.0 protocol message serialization and deserialization
Implements bidirectional JSON-RPC 2.0 message serialization using System.Text.Json with custom converters for MCP protocol types. The SDK handles request/response/notification message framing, error serialization with standardized error codes, and automatic message ID generation for request tracking. Built on top of ModelContextProtocol.Core package with pluggable JSON serialization configuration to support custom type converters and null-handling strategies.
Unique: Uses System.Text.Json source generators for zero-reflection serialization at compile-time, reducing runtime overhead compared to reflection-based JSON libraries. Provides MCP-specific type converters that handle protocol-level concerns like capability negotiation and resource subscription serialization.
vs alternatives: Faster and more memory-efficient than Newtonsoft.Json-based implementations due to source generation, with native .NET 6+ integration and no external dependencies beyond the SDK itself.
mcp server creation and capability registration
Provides a fluent builder API for configuring MCP servers with tool, prompt, and resource capabilities. The ServerOptions builder pattern allows declarative registration of handlers via dependency injection, with automatic parameter resolution from method signatures. Supports both standalone servers and ASP.NET Core integration, with built-in support for request/response filtering, cancellation tokens, and structured error handling. The server manages the full lifecycle including initialization, capability advertisement, and graceful shutdown.
Unique: Implements automatic parameter resolution from method signatures using reflection and Roslyn source generators, eliminating manual parameter mapping. Integrates directly with Microsoft.Extensions.DependencyInjection, allowing capabilities to depend on any registered service without explicit wiring.
vs alternatives: More declarative and type-safe than manual JSON-RPC handler registration, with compile-time verification of tool schemas via Roslyn analyzers that catch schema mismatches before runtime.
long-running task management with progress reporting
Provides infrastructure for managing tool invocations that take significant time to complete, with built-in progress reporting to clients. Tools can report progress updates during execution, and clients receive notifications of progress changes. The SDK handles progress state management, client notification delivery, and task cancellation. Supports both determinate progress (percentage complete) and indeterminate progress (activity indication).
Unique: Integrates progress reporting directly into the MCP protocol with automatic client notification, allowing LLMs to understand task progress without polling. Supports both determinate and indeterminate progress with structured progress data.
vs alternatives: More efficient than polling-based progress tracking, with push-based notifications reducing client overhead for long-running operations.
resource subscription and change notification system
Enables servers to push resource change notifications to subscribed clients without requiring polling. Clients subscribe to resources with optional filters, and servers send notifications when resource content changes. The SDK manages subscription state, client notification delivery, and cleanup on unsubscription. Supports both full content updates and delta updates for efficient bandwidth usage. Includes automatic resubscription on connection recovery.
Unique: Implements server-initiated push notifications for resource changes, allowing clients to receive updates without polling. Supports both full and delta updates with automatic subscription lifecycle management.
vs alternatives: More efficient than polling-based resource monitoring, with push-based notifications reducing latency and bandwidth for real-time resource synchronization.
asp.net core server integration with middleware support
Provides seamless integration of MCP servers into ASP.NET Core applications via dedicated middleware and service registration extensions. The integration allows MCP servers to run alongside standard ASP.NET Core endpoints, sharing dependency injection, configuration, and authentication/authorization infrastructure. Supports both HTTP transport and stdio transport for MCP communication. Includes automatic OpenAPI/Swagger documentation generation for MCP capabilities.
Unique: Provides first-class ASP.NET Core integration with automatic middleware registration and shared dependency injection, eliminating the need for separate MCP server processes. Supports both HTTP and stdio transports within the same ASP.NET Core application.
vs alternatives: More integrated than standalone MCP servers, with shared authentication, configuration, and dependency injection reducing operational complexity.
cancellation and error handling with structured error codes
Implements comprehensive cancellation support via CancellationToken throughout the SDK, allowing clients to cancel long-running operations. Provides structured error handling with standardized MCP error codes (parse error, invalid request, method not found, etc.) and detailed error messages. Errors include optional error data for additional context. Supports both synchronous and asynchronous error handling with proper exception propagation.
Unique: Implements cancellation as a first-class concept with CancellationToken support throughout the SDK, allowing graceful cancellation of long-running operations. Provides structured error codes aligned with JSON-RPC 2.0 specification.
vs alternatives: More robust than unstructured error handling, with standardized error codes and cancellation support enabling proper error recovery in client applications.
roslyn analyzers and source generators for compile-time verification
Provides Roslyn-based analyzers that verify MCP server implementations at compile-time, catching common errors before runtime. Source generators emit boilerplate code for tool registration, parameter resolution, and schema generation, eliminating manual code writing. Analyzers check for schema mismatches between tool definitions and implementations, missing required parameters, and invalid capability configurations. Generators produce efficient, reflection-free code for handler invocation.
Unique: Uses Roslyn source generators to emit zero-reflection handler code at compile-time, eliminating runtime reflection overhead. Includes custom analyzers that verify schema consistency between tool definitions and implementations.
vs alternatives: More efficient than reflection-based implementations, with compile-time code generation producing optimized handler invocation code and compile-time verification catching errors before runtime.
client-side oauth flow and token management
Implements OAuth 2.0 client-side flows for authenticating with OAuth-protected MCP servers. Handles authorization code flow with automatic redirect URI handling, token exchange, and token refresh. Manages token storage in client session with automatic token refresh before expiration. Supports both interactive (user-initiated) and non-interactive (client credentials) flows. Integrates with platform-specific authentication UI for user consent.
Unique: Implements automatic token refresh with expiration tracking, eliminating manual token management in client code. Supports both interactive and non-interactive flows with platform-specific UI integration.
vs alternatives: More convenient than manual OAuth implementation, with automatic token refresh and session management reducing client code complexity.
+9 more capabilities