---
title: "Implicit toolbelt (ReAct) · agent building block · Agent Fieldbook"
url: https://agentfieldbook.org/design/building_blocks/react-toolbelt/
description: "No formal ontology, the model reasons over natural-language tool descriptions injected into the prompt. Flexible, but the \"schema\" lives only in the LLM's interpretation."
section: "Design · Building Blocks · Ontology"
source: Agent Fieldbook — generated from the published page
---

# Implicit toolbelt (ReAct)

No formal ontology, the model reasons over natural-language tool descriptions injected into the prompt. Flexible, but the "schema" lives only in the LLM's interpretation.

## How it works

## At a glance

| Field | Value |
| --- | --- |
| Kind | Ontology· Implicit |
| Example | ReAct |

## Basis

- [arxiv.org](https://arxiv.org/abs/2210.03629)