> ## Documentation Index
> Fetch the complete documentation index at: https://docs.jelou.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Your First Tool

> Create your first Tool from scratch: build the flow, define inputs and outputs, and publish it to reuse across your flows.

**Tools** are reusable functions that execute <u>specific actions</u> within your flows: querying APIs, performing calculations, updating data, or automating tasks. They run instantly, return a result, and can be used across multiple Workflows and projects. Jelou includes native Tools ready to use, but you can also create your own when you need something specific to your business.\
\
In this guide you will build your first Tool: a simple function that queries the weather for a city and returns the temperature.

<Steps>
  <Step title="Create a new Tool">
    In the left panel of Brain Studio, go to the **Tools** tab and click to create a new Tool. Assign the name: **Check Weather**.
  </Step>

  <Step title="Drag an API node">
    On the canvas, drag an **API** node from the nodes panel. In the **URL** tab, enter:

    ```txt url.txt theme={null}
    https://api.weather.com/v1/current
    ```

    Under **Variables**, select or create an environment variable for your API key (mark it as secret if it contains credentials).
  </Step>

  <Step title="Configure the inputs">
    In the Tool configuration, add an input:

    * **Name**: `city`
    * **Type**: `string`
    * **Required**: Yes

    Configure how this input is sent to the API node (for example, as a URL parameter: `{{$input.city}}`).
  </Step>

  <Step title="Configure the outputs">
    Define what information the Tool will return. In the outputs configuration, map:

    * `temperature`: Extract the value from the API response
    * `description`: Extract the weather description

    These values will be available when you use the Tool in a Workflow.
  </Step>

  <Step title="Test your Tool">
    Use the testing functionality and enter a sample value, such as "Madrid". Verify that the response is correct and that the outputs are mapped properly.
  </Step>

  <Step title="Publish the Tool">
    Click **Publish**. A version (v1.0.0) will be generated and it will become available for use in any project within your company.
  </Step>
</Steps>

And that's it! You can now use this Tool in your Workflows by dragging it from the Tools panel and configuring the `city` input.