Claude Code adds CLAUDE_CODE_SUBAGENT_EFFORT to set a lower effort for subagents

Claude Code's @bcherny said the environment variable CLAUDE_CODE_SUBAGENT_EFFORT has landed. Running CLAUDE_CODE_SUBAGENT_EFFORT=low claude sets the effort level subagents use, and it can also be set in a custom agent's config. He was replying to a user who asked whether subagents could default to a lower effort instead of inheriting the main session's.