Chat Completions Skill not available with Purview Labels in Azure Search Indexer

Question

Chat Completions Skill not available with Purview Labels in Azure Search Indexer

Sigita Lapina 5

Hello,

We are starting to introduce Microsoft Purview sensitivity labels, and as a result, we need to change how we create indexes in Azure AI Search.

According to the documentation, custom skills are listed as a limitation. The Chat Completion skill is not explicitly mentioned, but since it is implemented as a Custom Web API skill, it appears to be affected by this limitation.

Is there a plan to enable support for the Chat Completion skill when using Purview sensitivity labels?

I would also like to point out what appears to be errors in Step 4, Step 6 and Step 7 of the documentation.

The index definition should include the following fields and properties in Step 4:

{
  "name": "sensitivityLabelId",
  "type": "Edm.String",
  "filterable": true,
  "retrievable": true,
  "sensitivityLabelId": true
},
{
  "name": "sensitivityLabelName",
  "type": "Edm.String",
  "filterable": true,
  "retrievable": true,
  "sensitivityLabelName": true
},
{
  "name": "sourceDocumentId",
  "type": "Edm.String",
  "searchable": false,
  "filterable": true,
  "retrievable": true,
  "sourceDocumentId": true
}

In Step 6, 2 mappings seem to be missing, it should be:

{
	"name": "sensitivityLabelId",
    "source": "/document/metadata_sensitivity_label",
},
{
	"name": "sensitivityLabelName",
	"source": "/document/metadata_sensitivity_label_name"
},
{
	"name": "sourceDocumentId",
	"source": "/document/metadata_source_document_id"
}

There also seems to be a mistake in Step 7. The indexer needs these three field mappings:

"fieldMappings": [
  {
    "sourceFieldName": "metadata_sensitivity_label",
    "targetFieldName": "sensitivityLabelId"
  },
  {
    "sourceFieldName": "metadata_sensitivity_label_name",
    "targetFieldName": "sensitivityLabelName"
  },
  {
    "sourceFieldName": "metadata_source_document_id",
    "targetFieldName": "sourceDocumentId"
  }
]

0 comments

1 answer

Your answer

Answer 1

Jerald Felix 18,760 Volunteer Moderator

Hello Sigita Lapina ,

Greetings! Thanks for raising this question in the Q&A forum

The limitation applies specifically to the Custom Web API skill (#Microsoft.Skills.Custom.WebApiSkill). The Chat Completion skill, now documented as the GenAI Prompt skill, uses #Microsoft.Skills.Custom.ChatCompletionSkill. Despite the Custom namespace, Microsoft classifies it as a built-in Azure-hosted-model skill, not a Custom Web API skill. Therefore, the documented Custom Web API limitation does not identify the Chat Completion skill as unsupported.

Use the required preview API version

Configure the Purview-enabled index, data source, skillset, and indexer using api-version=2026-08-01-preview. The current Purview sensitivity-label indexing documentation requires this version.

Use the current index schema

The current schema uses one sensitivity-label field:

{
  "purviewEnabled": true,
  "fields": [
    {
      "name": "sensitivityLabel",
      "type": "Edm.String",
      "filterable": true,
      "retrievable": true,
      "sensitivityLabel": true
    }
  ]
}

The separate sensitivityLabelId, sensitivityLabelName, and sourceDocumentId fields shown in the question are not part of the current documented 2026-08-01-preview configuration. The indexed label value is the label GUID. Applications that require the display name must resolve it through the Purview label APIs.

Project the label when creating chunks

When the skillset uses Text Split or another chunking pattern, map /document/metadata_sensitivity_label to the sensitivityLabel field in every projected chunk. Otherwise, labeled chunk rows will not be filtered correctly at query time.

For a non-chunked index, the indexer mapping is:

{
  "sourceFieldName": "metadata_sensitivity_label",
  "targetFieldName": "sensitivityLabel"
}

Use the Chat Completion skill as a built-in skill

The Azure AI Search skills reference lists GenAI Prompt under built-in skills and Web API under custom skills. Its configuration is documented at GenAI Prompt skill.

Escalate a reproducible service rejection

If the indexer still returns an explicit unsupported-feature error for #Microsoft.Skills.Custom.ChatCompletionSkill, open an Azure Support request and include the complete indexer error, search service region, API version, UTC timestamp, request or correlation ID, and sanitized skillset definition. This would require service-side investigation because the published limitation only names the Custom Web API skill.

If this answer helps you kindly accept the answer which will help others who have similar questions.

Best Regards,

Jerald Felix.

Sigita Lapina 5 Reputation points

2026-09-08T09:55:29.23+00:00
Hi @Jerald Felix ,

Thank you for the response. However, I had already followed the current documentation before raising this question, including using api-version=2026-08-01-preview. The issues I reported are based on the actual responses from the Azure AI Search service, rather than on an interpretation of the documentation.

1. The documented sensitivityLabel index property is rejected by 2026-08-01-preview

I first tested the schema currently shown in Step 4 of the documentation. Creating the index with the documented sensitivityLabel property results in the following response (service name and local paths redacted):

Failed: 400 {"error":{"code":"","message":"The request is invalid. Details: The property 'sensitivityLabel' does not exist on type 'Microsoft.Azure.Search.V2026_08_01_Preview.SchemaField' or is not present in the API version '2026-08-01-preview'. Make sure to only use property names that are defined by the type."}} requests.exceptions.HTTPError: 400 Client Error: Bad Request for url: https://<search-service>.search.windows.net/indexes/test-labels-index?api-version=2026-08-01-preview

So simply repeating the schema from the documentation does not address the issue I reported: the service explicitly rejects that schema with the API version that the documentation instructs us to use.

The index can instead be created using the three properties I mentioned in my original question:

sensitivityLabelId

sensitivityLabelName

sourceDocumentId

This is why I raised the Step 4 documentation issue in the first place.

2. The Chat Completion skill is explicitly rejected as an incompatible feature

I also tested the statement that #Microsoft.Skills.Custom.ChatCompletionSkill is supported because it is not a Custom Web API skill.

Using an existing Purview-enabled index, creation of an indexer whose skillset contains #Microsoft.Skills.Custom.ChatCompletionSkill fails with the following service response (service name and local paths redacted):

Failed: 400 {"error":{"code":"","message":"Permission extracted is not supported for the indexer as it utilizes some incompatible features. Please update your configuration to remove the incompatible features to utilize permission extraction. Incompatible features are: Chat Completion skill"}} requests.exceptions.HTTPError: 400 Client Error: Bad Request for url: https://<search-service>.search.windows.net/indexers/another-labels-indexer?api-version=2026-08-01-preview

This is not an inference based on the Custom namespace. Azure AI Search itself explicitly identifies Chat Completion skill as an incompatible feature when permission extraction is enabled.

Therefore, the distinction between #Microsoft.Skills.Custom.WebApiSkill and #Microsoft.Skills.Custom.ChatCompletionSkill does not resolve the question. Regardless of how Microsoft classifies the skill in the documentation, the current service behavior prevents it from being used in this configuration.

This brings me back to my original question:

Is support for the Chat Completion / GenAI Prompt skill with Purview sensitivity-label/permission extraction planned, and if so, is there a timeline for that support?

3. The documentation issues remain

There is also a related documentation problem. To get the Purview-enabled index/indexer configuration working, I had to use the three fields from my original post (sensitivityLabelId, sensitivityLabelName, and sourceDocumentId) and their corresponding mappings.

That is why I reported the apparent errors in Steps 4, 6, and 7. The examples currently documented do not match the API contract/service behavior I am observing with 2026-08-01-preview.

Could you please verify these points against the actual 2026-08-01-preview service implementation, rather than referring me back to the same documentation that produced the errors above?

If the documented schema is expected to work, then I believe the 400 response for sensitivityLabel needs investigation. If the current service behavior is expected, then the documentation appears to require correction.

For these reasons, I cannot mark this question as resolved, as the original issue remains unresolved.

Chat Completions Skill not available with Purview Labels in Azure Search Indexer

1 answer

1. The documented sensitivityLabel index property is rejected by 2026-08-01-preview

2. The Chat Completion skill is explicitly rejected as an incompatible feature

3. The documentation issues remain

Your answer

1. The documented `sensitivityLabel` index property is rejected by `2026-08-01-preview`