middleware-patterns

You can add authentication and rate limiting to MCP server requests by implementing reusable middleware patterns using the McpMiddleware trait. This trait provides before_dispatch and after_dispatch hooks to intercept and modify requests across HTTP and Lambda transports.

Yes, you can inject session state into MCP tools using middleware. The middleware implementation supports SessionInjection and RequestContext, allowing you to pass session data and request context across your tools and dispatch handlers.

Yes, MCP middleware works with both HTTP and Lambda transports. The middleware patterns apply cross-cutting concerns like authentication, logging, and rate limiting consistently across both transport layers without requiring separate implementations.

The best way to log and time MCP dispatch handlers is by registering a logging middleware with the MCP server builder. Using the McpMiddleware trait, the after_dispatch hook captures timing data while before_dispatch logs incoming requests for observability.

You configure middleware registration order when building the MCP server. The server builder allows you to compose and register multiple middleware components sequentially, ensuring the execution order matches your cross-cutting concern priorities for request interception.

You need the McpMiddleware trait to standardize cross-cutting concerns like auditing and security across all tools. It defines the before_dispatch and after_dispatch hooks required to intercept requests and return DispatcherResult without duplicating logic in individual handlers.