Subagents offload context-expensive work. The caller receives a digest, not the full trace. Default subagents are read-only (research, analyze, summarize). READ-WRITE subagents may modify state within declared scope.

When to Delegate

See contract § Subagent Delegation Protocol for authoritative triggers.

Summary:

Trigger	Threshold
Uncertain scope	Assess with cheap ops first → convert to defined
Content to read	>250KB of files to READ (not search scope)
Processing depth	>2 intermediate tool calls whose outputs aren't needed in final delivery

Clarification on 250KB:

Applies to Read operations (full content enters context)
Does NOT apply to Grep (only matches enter context)
Typical sequence: search (cheap) → identify matches → measure size of files to read → apply threshold

generic-subagent

When to Delegate