Performance

Phone tasks execute on real hardware at real-UI speed. Performance work here is not about shaving milliseconds - it is about sizing tasks correctly and setting the three timeout knobs deliberately.

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The three timeout knobs

Two useful properties:

• Paused time is free - time spent paused does not count against per_call_timeout_s.
• The monitor is not a deadline - monitor_timed_out: true never affects the task; it exists so your client never blocks forever.

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Size tasks like functions

The biggest performance lever is task granularity:

• One errand per task. Small tasks finish inside the default timeout, stay far from the agent’s action limit, and preserve progress on failure.
• iteration_limit is a design signal, not a retry candidate - the task exceeded the agent’s action budget and must be split.
• Chain in a session. Several focused tasks reusing one session_id outperform one mega-task on wall clock and reliability, because failures only repeat one step. See Cross-app workflows.

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Reduce queue contention

Each device runs one task at a time:

• Check phone_device_status before dispatching - an offline or busy device is wasted queue wait.
• Tasks started in the phone app hold the execution lane and keep MCP tasks pending; raise queue_wait_timeout_s when that is legitimate, or use a dedicated device for automation.
• Spread genuinely parallel workloads across multiple registered devices - one workflow per device.

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Keep the monitor loop lean

• Use phone_task_monitor as the wait primitive - one long-poll call - instead of hammering phone_task_status in a tight loop.
• Fetch steps incrementally: include_steps: true with since_step returns only new steps (screenshots, thinking) instead of the full history each time. Skip steps entirely when you only need the outcome.

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Prompt for speed

• Point the agent at the exact app and screen - “open WhatsApp, tab Chats” - so no time is spent exploring.
• Bound the ask: “first three events”, “the three cheapest flights”.
• Pre-answer predictable questions in the prompt (“if a dialog asks about notifications, dismiss it”) to avoid a round-trip through needs_user_control.

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