ServerHandlerCore Trait

ServerHandlerCore provides three methods that give you full control over every message:

Trait Definition

#[async_trait]
pub trait ServerHandlerCore: Send + Sync + 'static {
    async fn handle_request(
        &self,
        request: RequestFromClient,
        runtime: Arc<dyn McpServer>,
    ) -> Result<ResultFromServer, RpcError>;

    async fn handle_notification(
        &self,
        notification: NotificationFromClient,
        runtime: Arc<dyn McpServer>,
    ) -> Result<(), RpcError>;

    async fn handle_error(
        &self,
        error: &RpcError,
        runtime: Arc<dyn McpServer>,
    ) -> Result<(), RpcError>;
}

Example

#[async_trait]
impl ServerHandlerCore for MyCoreHandler {
    async fn handle_request(
        &self, request: RequestFromClient, runtime: Arc<dyn McpServer>,
    ) -> Result<ResultFromServer, RpcError> {
        match request {
            RequestFromClient::ListToolsRequest(_) => {
                Ok(ListToolsResult { tools: vec![], meta: None, next_cursor: None }.into())
            }
            RequestFromClient::CallToolRequest(params) => {
                Ok(CallToolResult::text_content(vec![TextContent::new(
                    "done".into(), None, None,
                )]).into())
            }
            _ => Err(RpcError::method_not_found()),
        }
    }

    async fn handle_notification(
        &self, _notification: NotificationFromClient, _runtime: Arc<dyn McpServer>,
    ) -> Result<(), RpcError> {
        Ok(())
    }

    async fn handle_error(
        &self, _error: &RpcError, _runtime: Arc<dyn McpServer>,
    ) -> Result<(), RpcError> {
        Ok(())
    }
}

Use .to_mcp_server_handler() to convert (same method name as the standard trait).