---
title: ReAct Agents
subtitle: Agents that reason and call tools in a loop
slug: guides/agents/architectures/react
---

ReAct agents are based on the [ReAct research paper](https://arxiv.org/abs/2210.03629) and follow a "Reason then Act" pattern. In Letta, agents using the ReAct architecture can reason and call tools in a loop (using the same heartbeat mechanism from MemGPT), but lack the **long-term memory capabilities** of MemGPT agents.

## Architecture

ReAct agents maintain conversation context through summarization but cannot edit their own memory or access historical messages beyond the context window.

**Key differences from MemGPT agents:**
* No read-write memory blocks or memory editing tools
* No access to evicted conversation history
* Simple conversation summarization instead of recursive memory management
* Tool calling without persistent state beyond the current session

**When to use ReAct agents:**
* Tool-calling tasks that don't require long-term memory
* Stateless interactions where conversation summarization is sufficient

## Creating ReAct Agents

To create a ReAct agent, simply use the `react_agent` agent type when creating your agent.
There is no need to pass any memory blocks to the agent, since ReAct agents do not have any long-term memory.

<CodeGroup>
```python title="python"
from letta_client import Letta

client = Letta(token="LETTA_API_KEY")

# create the ReAct agent
agent = client.agents.create(
    agent_type="react_agent",
    model="openai/gpt-4.1",
    embedding="openai/text-embedding-3-small",
    tools=["web_search", "run_code"]
)
```

```typescript title="node.js"
import { LettaClient } from '@letta-ai/letta-client'

const client = new LettaClient({ token: "LETTA_API_KEY" });

// create the ReAct agent
const agent = await client.agents.create({
    agentType: "react_agent",
    model: "openai/gpt-4.1",
    embedding: "openai/text-embedding-3-small",
    tools: ["web_search", "run_code"]
});
```

```bash title="curl"
curl -X POST https://api.letta.com/v1/agents \
     -H "Authorization: Bearer $LETTA_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
  "agent_type": "react_agent",
  "model": "openai/gpt-4.1",
  "embedding": "openai/text-embedding-3-small",
  "tools": ["web_search", "run_code"]
}'
```
</CodeGroup>