# operation-tags-defined

Source: https://apigenie.pl/docs/linter/openapi/rules/operation-tags-defined

This rule checks each operations' tags in an OpenAPI schema and warns if any
of them are empty lists.

## Rule Details

Tags help undertand the logical grouping of OpenAPI operations, which in turn
helps in using the API correctly.

The `operation-tags-defined` rule is designed to ensure that each operation in
an OpenAPI schema has at least one tag. Tags are used for logical grouping of
operations, which aids in understanding and using the API.

A situation when OpenAPI schema itself does not define any tags is not treated
as an issue.

## Configuration

None.

## Examples

**Good**. OpenAPI defines tags, which are used by an operation

```yaml
paths:
  /users:
    get:
      tags:
        - Users
      responses:
        "200":
          description: A list of users.
tags:
  - name: Users
```

**Good**. OpenAPI does not define any tags.

```yaml
paths:
  /users:
    get:
      responses:
        "200":
          description: A list of users.
```

**Bad**. Operation does not define any tags.

```yaml
paths:
  /users:
    get:
      responses:
        "200":
          description: A list of users.
tags:
  - name: Users
```

## When Not to Use It

When you decide not to use tags in your API contracts. In this case, the list
of tags in OpenAPI object should be empty.

## Compatibility

This rule is compatible with all OpenAPI 3.x versions.