Trait ServerHandler 

pub trait ServerHandler:
    Sized
    + Send
    + Sync
    + 'static {
    // Provided methods
    fn enqueue_task(
        &self,
        _request: CallToolRequestParams,
        _context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<CreateTaskResult, ErrorData>> + MaybeSendFuture { ... }
    fn ping(
        &self,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture { ... }
    fn initialize(
        &self,
        request: InitializeRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<InitializeResult, ErrorData>> + MaybeSendFuture { ... }
    fn supported_protocol_versions(&self) -> Cow<'static, [ProtocolVersion]> { ... }
    fn discover(
        &self,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<DiscoverResult, ErrorData>> + MaybeSendFuture { ... }
    fn complete(
        &self,
        request: CompleteRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<CompleteResult, ErrorData>> + MaybeSendFuture { ... }
    fn set_level(
        &self,
        request: SetLevelRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture { ... }
    fn get_prompt(
        &self,
        request: GetPromptRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<GetPromptResponse, ErrorData>> + MaybeSendFuture { ... }
    fn list_prompts(
        &self,
        request: Option<PaginatedRequestParams>,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<ListPromptsResult, ErrorData>> + MaybeSendFuture { ... }
    fn list_resources(
        &self,
        request: Option<PaginatedRequestParams>,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<ListResourcesResult, ErrorData>> + MaybeSendFuture { ... }
    fn list_resource_templates(
        &self,
        request: Option<PaginatedRequestParams>,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<ListResourceTemplatesResult, ErrorData>> + MaybeSendFuture { ... }
    fn read_resource(
        &self,
        request: ReadResourceRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<ReadResourceResponse, ErrorData>> + MaybeSendFuture { ... }
    fn subscribe(
        &self,
        request: SubscribeRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture { ... }
    fn unsubscribe(
        &self,
        request: UnsubscribeRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture { ... }
    fn call_tool(
        &self,
        request: CallToolRequestParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<CallToolResponse, ErrorData>> + MaybeSendFuture { ... }
    fn list_tools(
        &self,
        request: Option<PaginatedRequestParams>,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<ListToolsResult, ErrorData>> + MaybeSendFuture { ... }
    fn get_tool(&self, _name: &str) -> Option<Tool> { ... }
    fn on_custom_request(
        &self,
        request: CustomRequest,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<CustomResult, ErrorData>> + MaybeSendFuture { ... }
    fn on_cancelled(
        &self,
        notification: CancelledNotificationParam,
        context: NotificationContext<RoleServer>,
    ) -> impl Future<Output = ()> + MaybeSendFuture { ... }
    fn on_progress(
        &self,
        notification: ProgressNotificationParam,
        context: NotificationContext<RoleServer>,
    ) -> impl Future<Output = ()> + MaybeSendFuture { ... }
    fn on_initialized(
        &self,
        context: NotificationContext<RoleServer>,
    ) -> impl Future<Output = ()> + MaybeSendFuture { ... }
    fn on_roots_list_changed(
        &self,
        context: NotificationContext<RoleServer>,
    ) -> impl Future<Output = ()> + MaybeSendFuture { ... }
    fn on_task_status(
        &self,
        params: TaskStatusNotificationParam,
        context: NotificationContext<RoleServer>,
    ) -> impl Future<Output = ()> + MaybeSendFuture { ... }
    fn on_custom_notification(
        &self,
        notification: CustomNotification,
        context: NotificationContext<RoleServer>,
    ) -> impl Future<Output = ()> + MaybeSendFuture { ... }
    fn get_info(&self) -> InitializeResult { ... }
    fn list_tasks(
        &self,
        request: Option<PaginatedRequestParams>,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<ListTasksResult, ErrorData>> + MaybeSendFuture { ... }
    fn get_task_info(
        &self,
        request: GetTaskParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<GetTaskResult, ErrorData>> + MaybeSendFuture { ... }
    fn get_task_result(
        &self,
        request: GetTaskPayloadParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<GetTaskPayloadResult, ErrorData>> + MaybeSendFuture { ... }
    fn cancel_task(
        &self,
        request: CancelTaskParams,
        context: RequestContext<RoleServer>,
    ) -> impl Future<Output = Result<CancelTaskResult, ErrorData>> + MaybeSendFuture { ... }
}

Provided Methods

fn enqueue_task( &self, _request: CallToolRequestParams, _context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CreateTaskResult, ErrorData>> + MaybeSendFuture

fn ping( &self, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn initialize( &self, request: InitializeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<InitializeResult, ErrorData>> + MaybeSendFuture

fn supported_protocol_versions(&self) -> Cow<'static, [ProtocolVersion]>

Return the protocol versions supported by this server.

fn discover( &self, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<DiscoverResult, ErrorData>> + MaybeSendFuture

Return this server’s discovery information.

fn complete( &self, request: CompleteRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CompleteResult, ErrorData>> + MaybeSendFuture

fn set_level( &self, request: SetLevelRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn get_prompt( &self, request: GetPromptRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetPromptResponse, ErrorData>> + MaybeSendFuture

fn list_prompts( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListPromptsResult, ErrorData>> + MaybeSendFuture

fn list_resources( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListResourcesResult, ErrorData>> + MaybeSendFuture

fn list_resource_templates( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListResourceTemplatesResult, ErrorData>> + MaybeSendFuture

fn read_resource( &self, request: ReadResourceRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ReadResourceResponse, ErrorData>> + MaybeSendFuture

fn subscribe( &self, request: SubscribeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn unsubscribe( &self, request: UnsubscribeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn call_tool( &self, request: CallToolRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CallToolResponse, ErrorData>> + MaybeSendFuture

Handle a tools/call request from a client.

Choosing a return value

MCP distinguishes two failure modes; the API forces you to pick the right one explicitly because they reach the caller’s UI very differently:

• Ok(CallToolResult::error(...)) — the tool ran (or tried to) and produced a failure the caller should see. The content you supply is rendered in the caller’s MCP client, so the user gets your message. This is the right return value for almost every “the tool didn’t work” path — empty results, validation failures the user can fix, downstream service unavailability, etc.

• Err(McpError) — a JSON-RPC protocol error. Use this only when the request itself is unroutable: unknown tool (ErrorCode::METHOD_NOT_FOUND), malformed request shape that cannot be treated as a valid tools/call, or a server-internal failure that means the server cannot serve any request right now (ErrorCode::INTERNAL_ERROR, -32603). MCP clients typically render protocol errors opaquely; the caller will not see your message — they see something like “Tool result missing due to internal error”. If you want the caller to read your error, use Ok(CallToolResult::error(...)).

See CallToolResult::error for a worked example.

fn list_tools( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListToolsResult, ErrorData>> + MaybeSendFuture

fn get_tool(&self, _name: &str) -> Option<Tool>

Get a tool definition by name.

The default implementation returns None, which bypasses validation. When using #[tool_handler], this method is automatically implemented.

fn on_custom_request( &self, request: CustomRequest, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CustomResult, ErrorData>> + MaybeSendFuture

fn on_cancelled( &self, notification: CancelledNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_progress( &self, notification: ProgressNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_initialized( &self, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_roots_list_changed( &self, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_task_status( &self, params: TaskStatusNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_custom_notification( &self, notification: CustomNotification, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn get_info(&self) -> InitializeResult

fn list_tasks( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListTasksResult, ErrorData>> + MaybeSendFuture

fn get_task_info( &self, request: GetTaskParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetTaskResult, ErrorData>> + MaybeSendFuture

fn get_task_result( &self, request: GetTaskPayloadParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetTaskPayloadResult, ErrorData>> + MaybeSendFuture

fn cancel_task( &self, request: CancelTaskParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CancelTaskResult, ErrorData>> + MaybeSendFuture

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl<T> ServerHandler for Arc<T>

where T: ServerHandler,

fn enqueue_task( &self, request: CallToolRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CreateTaskResult, ErrorData>> + MaybeSendFuture

fn ping( &self, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn initialize( &self, request: InitializeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<InitializeResult, ErrorData>> + MaybeSendFuture

fn supported_protocol_versions(&self) -> Cow<'static, [ProtocolVersion]>

fn discover( &self, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<DiscoverResult, ErrorData>> + MaybeSendFuture

fn complete( &self, request: CompleteRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CompleteResult, ErrorData>> + MaybeSendFuture

fn set_level( &self, request: SetLevelRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn get_prompt( &self, request: GetPromptRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetPromptResponse, ErrorData>> + MaybeSendFuture

fn list_prompts( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListPromptsResult, ErrorData>> + MaybeSendFuture

fn list_resources( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListResourcesResult, ErrorData>> + MaybeSendFuture

fn list_resource_templates( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListResourceTemplatesResult, ErrorData>> + MaybeSendFuture

fn read_resource( &self, request: ReadResourceRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ReadResourceResponse, ErrorData>> + MaybeSendFuture

fn subscribe( &self, request: SubscribeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn unsubscribe( &self, request: UnsubscribeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn call_tool( &self, request: CallToolRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CallToolResponse, ErrorData>> + MaybeSendFuture

fn list_tools( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListToolsResult, ErrorData>> + MaybeSendFuture

fn get_tool(&self, name: &str) -> Option<Tool>

fn on_custom_request( &self, request: CustomRequest, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CustomResult, ErrorData>> + MaybeSendFuture

fn on_cancelled( &self, notification: CancelledNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_progress( &self, notification: ProgressNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_initialized( &self, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_roots_list_changed( &self, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_task_status( &self, params: TaskStatusNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_custom_notification( &self, notification: CustomNotification, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn get_info(&self) -> InitializeResult

fn list_tasks( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListTasksResult, ErrorData>> + MaybeSendFuture

fn get_task_info( &self, request: GetTaskParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetTaskResult, ErrorData>> + MaybeSendFuture

fn get_task_result( &self, request: GetTaskPayloadParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetTaskPayloadResult, ErrorData>> + MaybeSendFuture

fn cancel_task( &self, request: CancelTaskParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CancelTaskResult, ErrorData>> + MaybeSendFuture

impl<T> ServerHandler for Box<T>

where T: ServerHandler,

fn enqueue_task( &self, request: CallToolRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CreateTaskResult, ErrorData>> + MaybeSendFuture

fn ping( &self, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn initialize( &self, request: InitializeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<InitializeResult, ErrorData>> + MaybeSendFuture

fn supported_protocol_versions(&self) -> Cow<'static, [ProtocolVersion]>

fn discover( &self, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<DiscoverResult, ErrorData>> + MaybeSendFuture

fn complete( &self, request: CompleteRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CompleteResult, ErrorData>> + MaybeSendFuture

fn set_level( &self, request: SetLevelRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn get_prompt( &self, request: GetPromptRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetPromptResponse, ErrorData>> + MaybeSendFuture

fn list_prompts( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListPromptsResult, ErrorData>> + MaybeSendFuture

fn list_resources( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListResourcesResult, ErrorData>> + MaybeSendFuture

fn list_resource_templates( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListResourceTemplatesResult, ErrorData>> + MaybeSendFuture

fn read_resource( &self, request: ReadResourceRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ReadResourceResponse, ErrorData>> + MaybeSendFuture

fn subscribe( &self, request: SubscribeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn unsubscribe( &self, request: UnsubscribeRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<(), ErrorData>> + MaybeSendFuture

fn call_tool( &self, request: CallToolRequestParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CallToolResponse, ErrorData>> + MaybeSendFuture

fn list_tools( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListToolsResult, ErrorData>> + MaybeSendFuture

fn get_tool(&self, name: &str) -> Option<Tool>

fn on_custom_request( &self, request: CustomRequest, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CustomResult, ErrorData>> + MaybeSendFuture

fn on_cancelled( &self, notification: CancelledNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_progress( &self, notification: ProgressNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_initialized( &self, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_roots_list_changed( &self, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_task_status( &self, params: TaskStatusNotificationParam, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn on_custom_notification( &self, notification: CustomNotification, context: NotificationContext<RoleServer>, ) -> impl Future<Output = ()> + MaybeSendFuture

fn get_info(&self) -> InitializeResult

fn list_tasks( &self, request: Option<PaginatedRequestParams>, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<ListTasksResult, ErrorData>> + MaybeSendFuture

fn get_task_info( &self, request: GetTaskParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetTaskResult, ErrorData>> + MaybeSendFuture

fn get_task_result( &self, request: GetTaskPayloadParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<GetTaskPayloadResult, ErrorData>> + MaybeSendFuture

fn cancel_task( &self, request: CancelTaskParams, context: RequestContext<RoleServer>, ) -> impl Future<Output = Result<CancelTaskResult, ErrorData>> + MaybeSendFuture

Implementors

impl ServerHandler for ProxyHandler