The task tool — model-facing delegation

Java · package io.github.muthuishere:toolnexus · SPEC §7D · agents/AgentRuntime.java

Not available in Java

Only JS exposes a constructible task tool symbol; elsewhere it is the task builtin, toggled on the runtime.

The opt-in tool that lets the model itself spawn a teammate. Default OFF.

What to use instead

There is no standalone, constructible taskTool(...) symbol in this port — you cannot build one and drop it into an arbitrary extraTools list the way JS’s agents.taskTool allows. In Java, AgentRuntime builds the task tool itself, privately, and registers it on a handle’s own tool list automatically — the opt-in switch is declaring a team, not constructing a tool object:

// AgentSpec.team(...) IS the opt-in — spec.team = empty ⇒ no `task` tool at all.
Agents.Agent coordinator = Agents.agent("coordinator", new Agents.AgentSpec()
        .does("splits work and delegates")
        .model("gpt-4o-mini")
        .team(worker, researcher)); // <- declaring a team is the switch

// Equivalently at the AgentDef level (agents.AgentRuntime.java):
AgentDef def = new AgentDef("coordinator", "splits work and delegates", "", "gpt-4o-mini")
        .team(List.of("worker", "researcher"));

Internally, AgentRuntime.executeTurn checks h.def.team != null && !h.def.team.isEmpty() and only then adds the private task tool to that turn’s toolkit — recursion and delegation are opt-in per agent, never default, and a child gets no task reach unless its own def declares a team. The tool’s description is composed for the model from each team member’s does field, name-sorted; calling task {agent, prompt} fuses spawn→wake→wait→close into one tool call, and a re-invoked call with the same {agent, prompt} pair reattaches to the existing child rather than spawning a duplicate (the durable-resume idempotency rule).

If you want the same fused behavior without a model choosing the target — scripted, deterministic delegation — call Agents.Agent.run directly instead of going through a model-facing tool at all.

See also

• agents.Agent — AgentSpec.team(...) is the opt-in switch that registers task.
• agents.Runtime — the six host verbs task fuses into one call.
• agents.Handle — the child handle a task call spawns, waits on, and closes.
• agents.Budget — bounds what a delegated task call may spend.