> ## Documentation Index > Fetch the complete documentation index at: https://gofastmcp.com/llms.txt > Use this file to discover all available pages before exploring further. # tasks # `fastmcp.client.tasks` SEP-1686 client Task classes. ## Classes ### `TaskNotificationHandler` MessageHandler that routes task status notifications to Task objects. **Methods:** #### `dispatch` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} dispatch(self, message: Message) -> None ``` Dispatch messages, including task status notifications. ### `Task` Abstract base class for MCP background tasks (SEP-1686). Provides a uniform API whether the server accepts background execution or executes synchronously (graceful degradation per SEP-1686). **Methods:** #### `task_id` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} task_id(self) -> str ``` Get the task ID. #### `returned_immediately` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} returned_immediately(self) -> bool ``` Check if server executed the task immediately. **Returns:** * True if server executed synchronously (graceful degradation or no task support) * False if server accepted background execution #### `on_status_change` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} on_status_change(self, callback: Callable[[GetTaskResult], None | Awaitable[None]]) -> None ``` Register callback for status change notifications. The callback will be invoked when a notifications/tasks/status is received for this task (optional server feature per SEP-1686 lines 436-444). Supports both sync and async callbacks (auto-detected). **Args:** * `callback`: Function to call with GetTaskResult when status changes. Can return None (sync) or Awaitable\[None] (async). #### `status` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} status(self) -> GetTaskResult ``` Get current task status. If server executed immediately, returns synthetic completed status. Otherwise queries the server for current status. #### `result` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} result(self) -> TaskResultT ``` Wait for and return the task result. Must be implemented by subclasses to return the appropriate result type. #### `wait` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} wait(self) -> GetTaskResult ``` Wait for task to reach a specific state or complete. Uses event-based waiting when notifications are available (fast), with fallback to polling (reliable). Optimally wakes up immediately on status changes when server sends notifications/tasks/status. **Args:** * `state`: Desired state ('working', 'input\_required', 'completed', 'failed', 'cancelled'). If None, waits until the task exits the 'working' state (completed, failed, cancelled, input\_required, etc.) * `timeout`: Maximum time to wait in seconds **Returns:** * Final task status **Raises:** * `TimeoutError`: If desired state not reached within timeout #### `cancel` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} cancel(self) -> None ``` Cancel this task, transitioning it to cancelled state. Sends a tasks/cancel protocol request. The server will attempt to halt execution and move the task to cancelled state. Note: If server executed immediately (graceful degradation), this is a no-op as there's no server-side task to cancel. ### `ToolTask` Represents a tool call that may execute in background or immediately. Provides a uniform API whether the server accepts background execution or executes synchronously (graceful degradation per SEP-1686). **Methods:** #### `result` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} result(self) -> CallToolResult ``` Wait for and return the tool result. If server executed immediately, returns the immediate result. Otherwise waits for background task to complete and retrieves result. **Returns:** * The parsed tool result (same as call\_tool returns) ### `PromptTask` Represents a prompt call that may execute in background or immediately. Provides a uniform API whether the server accepts background execution or executes synchronously (graceful degradation per SEP-1686). **Methods:** #### `result` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} result(self) -> mcp.types.GetPromptResult ``` Wait for and return the prompt result. If server executed immediately, returns the immediate result. Otherwise waits for background task to complete and retrieves result. **Returns:** * The prompt result with messages and description ### `ResourceTask` Represents a resource read that may execute in background or immediately. Provides a uniform API whether the server accepts background execution or executes synchronously (graceful degradation per SEP-1686). **Methods:** #### `result` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} result(self) -> list[mcp.types.TextResourceContents | mcp.types.BlobResourceContents] ``` Wait for and return the resource contents. If server executed immediately, returns the immediate result. Otherwise waits for background task to complete and retrieves result. **Returns:** * list\[ReadResourceContents]: The resource contents