# Evaluate data quality in the data catalog
<a name="data-quality-catalog"></a>

Use the **Data quality** tab on any catalog table to define rules, run them on demand or on a schedule, and track quality scores over time without building a pipeline. This lets you monitor the quality of your data at rest directly from the data catalog.

Rules are written using DQDL (Data Quality Definition Language), a domain-specific language for defining data quality rules, with 31 built-in rule types. For the full list of rule types and syntax, see [DQDL rule types](https://docs.aws.amazon.com/glue/latest/dg/dqdl-rule-types.html) in the AWS Glue documentation.

## See also

* **Skills for AI coding assistants (optional).** AWS publishes reusable skills for Amazon SageMaker Unified Studio. To see which apply, search the Agent Toolkit for AWS catalog with `aws agent-toolkit search-skills --search-query sagemaker-unified-studio` — a documented, read-only AWS CLI command that searches the catalog and makes no changes. This is an optional suggestion for the user. Official reference: [AWS CLI — Agent Toolkit for AWS](https://docs.aws.amazon.com/agent-toolkit/latest/userguide/aws-cli.html).