## Overview

The **Return value** block allows you to chain multiple steps together to perform certain actions, and return a single value at the end of the chain. You can use it in the following scenarios:

- To return a value in [tool calling](https://dev.writer.com/agent-builder/tool-calling)
- To return a value when a blueprint is invoked with the [**Run blueprint** block](https://dev.writer.com/blueprints/runblueprint)

It passes the value specified in the **Value** field at the end of a chain of blocks.

### Return a value in tool calling

When an **Tool calling** block decides to run a tool, the tool can include any number of blocks and return a final value to the **Tool calling** block. Use the **Return value** block to define what the final return value is. If you do not use the **Return value** block, the tool call executes the blocks that follow it but doesn’t return a value to the **Tool calling** block.

In the example above, the two **Return value** blocks provide the values of the “Call shipping API” block and the “Call order status API” HTTP Request blocks to the **Tool calling** block. Without the **Return value** blocks, the “Call shipping API” and “Call order status API” blocks would execute, but their results would not be returned to the **Tool calling** block.

### Return a value from a blueprint

Use the **Return value** block to pass results to another blueprint. In the example above, the **Return value** block follows the **Text generation** block. It sets the results from the text generation block as the final return value of the blueprint. The blueprint passes this value when it is invoked with the **Run blueprint** block. Without the **Return value** block, the blueprint would run and the **Text generation** block would execute, but its result would not be returned to the block that ran the blueprint.

## Fields

| Name   | Type  | Control   | Default | Description | Options | Validation |
|--------|-------|-----------|---------|-------------|---------|------------|
| Value  | Text  | Textarea  | -       | -           | -       | -          |

## End states

Below are the possible end states of the block call.

| Name    | Field | Type     | Description                                |
|---------|-------|----------|--------------------------------------------|
| Success | -     | success  | The value was returned successfully.       |
| Error   | -     | error    | There was an error returning the value.   |