Difference between a tool call and a subagent call?

Difference between a tool call and a subagent call?medium

Type: conceptual
Topic: between-a-tool-call-and-a-subagent-call
Frequency: common
Tags: ai-agents, difference, between, tool, call, and

Answer

Tool call: agent invokes a deterministic function (API, DB query, calculator) — takes inputs, returns outputs, no reasoning.

Explanation

Tool call: agent invokes a deterministic function (API, DB query, calculator) — takes inputs, returns outputs, no reasoning. Subagent call: agent delegates to another agent with its own LLM, system prompt, memory, and tools. Subagent can reason and make multi-step decisions. Use tools for simple deterministic actions; subagents for complex stateful subtasks that require reasoning.

Follow-upWhen would you choose one approach over the other?