# Subagent

> A subagent is a specialist agent a primary agent delegates to — running in its own context window with its own prompt and tools, returning only a summary.

**A subagent is an agent invoked by another agent: a specialist with its own context window, system prompt, and (usually restricted) toolset, which does a delegated job and returns a clean summary to its parent.**

The mechanism buys three things a single thread can't. **Isolation** — a log-trawling investigation burns tokens in the subagent's [context](/glossary/context-window), not yours. **Specialization** — a focused prompt ("you review diffs for security issues; nothing else") outperforms a generalist on its niche. **Safety** — a reviewer with read-only tools physically can't edit code. Those properties make subagents the building block of every [multi-agent pattern](/guides/advanced/multi-agent-orchestration): fan-out, pipelines, orchestrator-worker, and fresh-eyes critics.

In Claude Code they're first-class and file-defined — a Markdown file whose `description` doubles as the delegation router ([getting started](/guides/getting-started/getting-started-with-agents), [writing a good one](/guides/getting-started/writing-a-custom-agent)) — and the hub's [agents directory](/agents) is a library of ready-made ones. The discipline that keeps them useful: one nameable job per agent, and remember they start blank — every constraint must be passed in, because a subagent sees nothing of the parent's conversation.

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_Source: https://agentscamp.com/glossary/subagent — Term on AgentsCamp._