A task from the MCP Tasks extension (io.modelcontextprotocol/tasks), available under MCP 2026-07-28.

A tool handler may answer a call with a task instead of a result, and the client polls for the outcome. Return one from the handler and Phantom responds with a CreateTaskResult:

def export_report(params, session) do
  task = MyApp.MCPTasks.create!(session, params)
  {:reply, Phantom.Tasks.new(id: task.id, status: :working, created_at: task.inserted_at), session}
end

Phantom does not store tasks. You store them, run the work, and move them through their statuses; Phantom asks your router for them when the client polls. Check Phantom.Session.tasks_supported?/1 before returning a task, since a client that did not declare the extension cannot receive one.

Return the task from the handler. Phantom.Session.respond/2 does not accept one, since the task is already the asynchronous answer. Only tools answer with tasks.

Fields

• :id - (required) The task ID. It acts as a bearer token, so it must be unguessable; see generate_id/0.
• :status - (required) One of :working, :input_required, :completed, :failed, or :cancelled. Strings are accepted.
• :created_at - (required) A DateTime.
• :last_updated_at - A DateTime. Defaults to :created_at.
• :status_message - An optional message describing the current status.
• :ttl_ms - Milliseconds from creation that the task is kept, or nil for unlimited.
• :poll_interval_ms - Suggested milliseconds between client polls.
• :input_requests - Required when :input_required. A map of keys to Phantom.Elicit structs or embedded request maps. Keys must not be reused over the task's lifetime.
• :result - Required when :completed. The final CallToolResult, such as Phantom.Tool.response(Phantom.Tool.text("Done")). A tool error is still :completed.
• :error - Required when :failed. A JSON-RPC error with :code and :message, such as Phantom.Request.internal_error("Timed out").