Agent roles are optional overlays

Status: accepted

The Agent tool takes an optional role. Omitting the role creates a default child that inherits the delegating agent's effective instructions, tools, model policy, and delegation capability while sharing the root session's dynamic permission policy; a named role applies its own specialization as a configuration overlay. Roles therefore guide or specialize agents without creating distinct runtime classes, allowing homogeneous recursive swarms without a duplicated built-in worker runtime.

Decision history

A required subagent_type selector was replaced with optional role selection. Default inheritance supports homogeneous recursive delegation without a separate worker runtime; named roles supply their own specialization.