Agent Coordination

Tools the agent uses to plan, delegate and ask for help.

Besides doing the work, the agent has tools for organizing it: planning multi-step jobs, delegating to specialists, spawning sub-agents, and pausing to ask you when something is genuinely unclear.

Tools in this family

Tool	What it does
todo	Rewrites the session to-do list across a long task. The chat shows it as a checklist that ticks off as work progresses.
spawn_subagent	Delegates to a reusable async specialist. It creates a fresh worker only when the work is incompatible or you ask.
spawn_async_subagent	A lower-level reusable async delegation tool with the same durable session identity.
steer_subagent, wait_subagent	Message or collect a running worker by durable subagent_session_id or transient task_id.
list_subagents, close_subagent	Inspect the reusable workers for the parent thread, or retire one.
spawn_worker_thread	Explicit background work tracked as a separate worker thread.
delegate	Hands a task to a specialist, such as an archetype with different prompts, tools or permissions.
spawn_parallel_agents	Fans one task out to several specialists at once and merges what they return.
use_skill	Loads an inline skill's playbook and tools (coding, web3, system, scheduling, docs, mcp) so the agent can call them.
ask_user_clarification	Pauses and asks you a precise question instead of guessing.
plan_exit	Leaves the planning phase and starts executing.

spawn_subagent and archetype delegation calls accept an optional model field to pin an exact model for one call. If you leave it out, the harness uses per-agent pins from config when present, and otherwise falls back to normal model-routing hints. Model, sandbox mode, parent thread, action root and task key all affect whether a sub-agent can be reused, so materially different work gets its own worker.

Reusable delegation returns a transient task_id and a durable subagent_session_id. Use the durable id for follow-ups in later turns. Pass fresh: true only when you or the task needs a clean worker. Pass blocking: true only when the parent must wait for the child's result.

Why these are tools

Long tasks fall apart when an agent tries to hold everything in one head. Splitting work with to-dos and sub-agents helps in three ways:

• Each sub-agent keeps useful local context for the same job instead of being respawned every turn.

• The main thread keeps a high-level view of progress.

• A failure in one branch does not spoil the rest.

Asking for clarification is a tool on purpose. It makes "I should ask the user" a visible decision the agent can be steered toward, instead of something that only happens by chance.

See also

• Coder: the coding tools, most of them loaded through the coding skill.

• Cron and scheduling: how background agent runs are scheduled.