Alert payload IRM forwards to Grafana Assistant is not being parsed correctly

Grafana Cloud Grafana IRM
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1

We’re using Grafana IRM to send alerts from our cluster to Grafana Cloud, and as part of this setup, we configured an Outgoing Webhook in Grafana IRM Integration to automatically trigger a new investigation in the Grafana Assistant Investigation API upon alert group creation.

Although we are sending a raw JSON payload with an alerts array, The Grafana assistant API responds with description “No alerts present.”

Outgoing webhook Details:

Source: Grafana OnCall Event Body (raw)

Destination API: https://xxx/api/plugins/grafana-assistant-app/resources/api/v1/investigations/from-irm

Trigger Type: Alert Group Created.

Response:

{
    "$schema": https://assistant-prod-us-east-0.grafana.net/schemas/ResponseBodyInvestigationResponse.json,
    "status": "success",
    "data": {
        "id": "c874641e-6487-4db3-b73a-fcf6c7d4b927",
        "title": "\n  <Title> - Investigation Report",
        "description": "Investigation report for: No alerts present in the request.\n",
        "state": "pending",
        "chatId": "480cdf6a-96ad-437d-a741-21b45e54c8e4",
        "createdAt": "2025-10-31T12:36:32Z",
        "updatedAt": "2025-10-31T12:36:32Z",
        "confidence": 0,
        "source": {
            "type": "url",
            "value": https://<domain>//a/grafana-irm-app/alert-groups/IHZVS79PUSMTC
        }
    }
}

Can someone help me with a valid JSON structure (schema) the Assistant Investigation API expects in the request body.