ModelRefs / Agent as Tool — AI Glossary
Agent as Tool — AI Glossary
A design pattern exposing a full AI agent as a callable tool for another agent, enabling hierarchical agent composition.
Overview
Agent-as-tool enables parent agents to delegate to specialized child agents by calling them as tool invocations. The child agent handles a complete sub-task and returns its result. Used in Claude's computer use (shell agent callable from a parent), LangGraph subgraphs, and CrewAI agent delegation. Enables modular, testable agent hierarchies.
Reference details
| Topic | agents |
|---|---|
| Also known as | nested agent, hierarchical agent |
| Last reviewed | 2026-06-24 |
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Frequently asked questions
What is Agent as Tool?
A design pattern exposing a full AI agent as a callable tool for another agent, enabling hierarchical agent composition.
Is Agent as Tool the same as nested agent?
Yes — nested agent, hierarchical agent are common aliases for Agent as Tool.
What concepts are related to Agent as Tool?
Closely related concepts include subagent, worker agent, tool agent.