Trait ClientHandler 

pub trait ClientHandler: Send + Sync {
    // Provided methods
    fn create_message(
        &self,
        _request: CreateMessageRequest,
    ) -> impl Future<Output = Result<CreateMessageResult, McpError>> + Send { ... }
    fn elicit(
        &self,
        _request: ElicitRequest,
    ) -> impl Future<Output = Result<ElicitResult, McpError>> + Send { ... }
    fn list_roots(
        &self,
    ) -> impl Future<Output = Result<Vec<Root>, McpError>> + Send { ... }
    fn on_connected(&self) -> impl Future<Output = ()> + Send { ... }
    fn on_disconnected(&self) -> impl Future<Output = ()> + Send { ... }
    fn on_task_progress(
        &self,
        _task_id: TaskId,
        _progress: TaskProgress,
    ) -> impl Future<Output = ()> + Send { ... }
    fn on_resource_updated(
        &self,
        _uri: String,
    ) -> impl Future<Output = ()> + Send { ... }
    fn on_resources_list_changed(&self) -> impl Future<Output = ()> + Send { ... }
    fn on_tools_list_changed(&self) -> impl Future<Output = ()> + Send { ... }
    fn on_prompts_list_changed(&self) -> impl Future<Output = ()> + Send { ... }
}

Handler trait for server-initiated requests.

Implement this trait to handle requests that servers send to clients. All methods have default implementations that return “not supported” errors.

Example

use mcpkit_client::ClientHandler;
use mcpkit_core::types::{CreateMessageRequest, CreateMessageResult};
use mcpkit_core::error::McpError;

struct MyHandler;

impl ClientHandler for MyHandler {
    // Override methods as needed to handle server requests
}

Provided Methods

fn create_message( &self, _request: CreateMessageRequest, ) -> impl Future<Output = Result<CreateMessageResult, McpError>> + Send

Handle a sampling request from the server.

The server is asking the client’s LLM to generate a response. This is used for agentic workflows where the server needs LLM capabilities.

Errors

Returns an error if sampling is not supported or the request fails.

fn elicit( &self, _request: ElicitRequest, ) -> impl Future<Output = Result<ElicitResult, McpError>> + Send

Handle an elicitation request from the server.

The server is asking for user input. The client should present the request to the user and return their response.

Errors

Returns an error if elicitation is not supported or the request fails.

fn list_roots(&self) -> impl Future<Output = Result<Vec<Root>, McpError>> + Send

List roots that the client exposes.

Roots are file system paths that the server can access. This is typically used for file-based operations.

Errors

Returns an error if roots are not supported.

fn on_connected(&self) -> impl Future<Output = ()> + Send

Called when the connection is established.

Override this to perform setup after initialization.

fn on_disconnected(&self) -> impl Future<Output = ()> + Send

Called when the connection is closed.

Override this to perform cleanup.

fn on_task_progress( &self, _task_id: TaskId, _progress: TaskProgress, ) -> impl Future<Output = ()> + Send

Called when a task makes progress.

Override this to track task progress updates from the server.

fn on_resource_updated(&self, _uri: String) -> impl Future<Output = ()> + Send

Called when a resource has been updated.

Override this to react to resource changes (requires subscription).

fn on_resources_list_changed(&self) -> impl Future<Output = ()> + Send

Called when the list of available resources has changed.

Override this to refresh your cached resource list.

fn on_tools_list_changed(&self) -> impl Future<Output = ()> + Send

Called when the list of available tools has changed.

Override this to refresh your cached tool list.

fn on_prompts_list_changed(&self) -> impl Future<Output = ()> + Send

Called when the list of available prompts has changed.

Override this to refresh your cached prompt list.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl ClientHandler for NoOpHandler

impl<F, Fut> ClientHandler for SamplingHandler<F>

where F: Fn(CreateMessageRequest) -> Fut + Send + Sync, Fut: Future<Output = Result<CreateMessageResult, McpError>> + Send,