Most Claude Code sessions get slow and cluttered for the same reason: every exploratory grep, every log dump, and every "let me check one more file" stays in the main conversation forever.
Subagents exist to fix exactly that problem. They are one of the agent primitives built into Claude Code for handling noisy, parallelizable work — a way to push the mess into an isolated window and bring back only the summary that matters.
A subagent is not a smarter Claude, and it is not the same thing as a Skill. It is a separate reasoning agent with its own context window, its own tool allowlist, and no memory of your current conversation unless you explicitly fork it. Understanding that distinction is the difference between a subagent setup that quietly saves you context budget and one that just adds latency for no benefit.
Subagents vs Skills vs MCP
Claude Code gives you three extension points that solve different problems, and they get conflated constantly because all three can technically "help with a task."
