# Agents

Agents use an LLM to determine which actions to take and in what order.
An action can either be using a tool and observing its output, or returning to the user.
For a list of easily loadable tools, see [here](tools.md).
Here are the agents available in LangChain.

For a tutorial on how to load agents, see [here](/getting_started/agents.ipynb).

### `zero-shot-react-description`

This agent uses the ReAct framework to determine which tool to use
based solely on the tool's description. Any number of tools can be provided.
This agent requires that a description is provided for each tool.

### `react-docstore`

This agent uses the ReAct framework to interact with a docstore. Two tools must
be provided: a `Search` tool and a `Lookup` tool (they must be named exactly as so).
The `Search` tool should search for a document, while the `Lookup` tool should lookup
a term in the most recently found document.
This agent is equivalent to the
original [ReAct paper](https://arxiv.org/pdf/2210.03629.pdf), specifically the Wikipedia example.

### `self-ask-with-search`

This agent utilizes a single tool that should be named `Intermediate Answer`.
This tool should be able to lookup factual answers to questions. This agent
is equivalent to the original [self ask with search paper](https://ofir.io/self-ask.pdf),
where a Google search API was provided as the tool.