Subagents vs skills: context isolation for agentic coding workflows

Source type	Practitioner
Confidence	Medium
Last verified	2026-03-22
Topics	claude-code

Insight: Subagents solve the context pollution problem in agentic coding: exploration and verification generate the most output, burying the main conversation in noise. Use skills when you want your current agent to follow a better procedure; use subagents when the work should happen in its own context and only the result matters. Subagents offer clean context isolation, parallelism, tool scoping, and model mixing.

Detail: Builder.io implements subagents via markdown files in .builder/agents/ with name, description, and tools list. The key insight is that subagents turn a single conversation into a coordinated team — each subagent gets a fresh context window for noisy work (search results, test output, exploration) and returns only a summary. This prevents the "scrolling through 400 lines of logs" problem that plagues long agentic sessions.

Sources

• Alice Moore / Builder.io — "Subagents: When and How to Use Them" (2026-02-03)
• Simon Willison — "Subagents" (Agentic Engineering Patterns guide)" (2026-03-17)
• Simon Willison — "Use subagents and custom agents in Codex" (2026-03-16)

Related: existing entry "Claude Code tips and workflows" in external/claude-code.md — COMPLEMENTS