The existing advice on a scoped service account is solid for initial containment. However, the "messy permissions" you've flagged have a subtle, long-term financial implication that often gets missed in these discussions.
When an agent has broad, unvetted access, it can trigger expensive operations you didn't budget for. For instance, an agent with read access to a broad directory tree in cloud storage could inadvertently scan millions of objects, incurring LIST or Class B operations charges. In a Jira context, a poorly scoped API token might allow the agent to execute expensive JQL queries across all projects, impacting your Atlassian rate limits and potentially the performance costs of your hosted instance.
Your sandboxing strategy should therefore include rate-limiting and cost-tracking from day one. Run your audit script not just for security, but to log and estimate the API call volume and data egress potential of each permitted path or endpoint. This gives you a cost profile for the agent's maximum possible behavior under its current permissions, which is a crucial data point for FinOps.
Always check the data transfer costs.