Your Microsoft 365 tenant was configured years ago, and employees can now create agents as easily as they share documents. When a creator leaves, the agent can remain. This guide shows where to find the inventory, what to record and where a basic ownership review stops.
The agent stays after its creator leaves
Microsoft describes a specific lifecycle gap for shared agents. When the creator's user account is deleted from the organisation, those agents become ownerless. The Agent Registry exposes a count and filter for them, then allows an authorised administrator to block or delete them (Microsoft Agent Registry, checked: 2026-10-05).
That behaviour resembles an old shared folder whose owner left. The difference is that an agent also carries instructions, channels and knowledge sources. A name such as "Sales helper" tells you little about what it can read or who still depends on it.
The counter updates when the user's account is hard-deleted, according to Microsoft's documentation. A firm that disables departed users and retains their accounts may therefore fail to see the gap in the ownerless count. That is an inference from the documented trigger, not a claim about every tenant configuration (Microsoft Agent Registry, checked: 2026-10-05).
The basic inventory is already available
Microsoft's service table says Microsoft 365 Business plans include the Agent Registry and basic actions without an Agent 365 licence. Those actions include publish, deploy, block, delete, approve, assign agents, reassign an owner and pin an agent. The same table places deeper monitoring, policy templates, tenant-wide tool controls, agent Conditional Access, Purview auditing and DLP behind Agent 365 or E7/G7 (Microsoft Agent 365 service description, checked: 2026-10-05).
This distinction keeps the first task proportionate. You do not need an observability project to answer "what exists and who owns it?" Start with the tools already available, then decide whether the remaining questions justify more controls.
The documented path is Agents, All Agents, Registry in the Microsoft 365 admin center. The screen shows Total agents, Agents without owners and Unmanaged agents. It also offers filters for status, publisher type, channel, platform and data source (Microsoft Agent Registry, checked: 2026-10-05).
Treat that register as part of ordinary Microsoft 365 permissions and licence housekeeping. An agent owner should be as visible as the owner of a shared site or business process.
Build an inventory someone can act on
Record the three counts
Open the Registry and write down the three headline numbers with the review date. A screenshot alone is weak evidence because it cannot carry a decision. Record who reviewed it and which tenant it came from.
If the counts are zero, check the limits before declaring the work finished. Microsoft says draft visibility currently applies only to Copilot Studio. Drafts created elsewhere, including Agent Builder or SharePoint, may not appear in that view (Agent 365 overview, checked: 2026-10-05).
Resolve agents without owners
Filter Agents without owners. For each result, choose one of three outcomes: assign a responsible owner, block it while the business checks its purpose, or remove it after confirming nobody relies on it.
Only AI Administrators and Global Administrators can perform key actions such as approving agent requests and assigning owners. If the reviewer lacks one of those roles, the register must include the administrator who can carry out the decision (Agent 365 overview, checked: 2026-10-05).
Do not make the departed employee the only reference point. Ask the department that used the agent what job it performed, which channel exposed it and what would break if it stopped.
Export and sort the registry
The registry can export all agents or a filtered list to CSV. Microsoft says the export contains more than 30 fields, including name, status, channel, created and modified dates, publisher, publisher type, owner, platform and instructions (Microsoft Agent Registry, checked: 2026-10-05).
Sort first by Owner, then Publisher type. Mark items listed as "Shared by creator," because their lifecycle depends closely on a person's account. Add three working columns outside the original export: business purpose, decision owner and review date.
The CSV is a decision sheet, not a permanent source of truth. Return completed ownership changes to the registry, then keep the dated export as evidence of the review.
Review embedded knowledge
Use the Data source filter to find Embedded knowledge. Microsoft defines this as content uploaded by the creator for the agent to use (Microsoft Agent Registry, checked: 2026-10-05).
Ask the current owner what those files are, whether they remain current and who may read their contents. Do not infer sensitivity from filenames. A bland document title can still contain customer, personnel or pricing information.
This is the same identity principle described in the guide to external file sharing and guest access: access needs a named subject and a reason. For an agent, add a named owner and a reviewed knowledge source.
Put agents into offboarding
Add an agent review before an employee account is deleted. Search the registry for the person's owned or published agents, transfer the ones the business needs and block the uncertain ones until a new owner decides.
Microsoft began automatically creating a Microsoft Entra Agent ID for each new Copilot Studio agent in July 2026, and the setting cannot be disabled at environment level. The identity can support agent-specific connector permissions, Conditional Access and DLP, although those advanced controls depend on licensing and administration beyond this checklist (Copilot Studio what's new, checked: 2026-10-05).
The practical point is simpler: agents have a lifecycle that now belongs in the same departure process as accounts, groups, mailboxes and shared files.
What not to do
Do not delete every ownerless agent in bulk. The missing owner is evidence of poor lifecycle control, not proof that nobody uses the agent.
Do not buy Agent 365 merely to obtain a list. Microsoft's current service description says the registry and basic ownership actions are included with Business plans (Microsoft Agent 365 service description, checked: 2026-10-05).
Do not assume an agent can access everything or nothing. Check its identity, permissions, tools and data sources. A registry review raises those questions; it does not answer all of them.
Do not assume a quiet dashboard proves an agent is unused. Microsoft says activity metrics such as Active users, Agent run-time and Agents with exceptions start collecting after Agent 365 activation (Agent 365 overview, checked: 2026-10-05).
When you can handle this yourself
A small firm can run the first review internally when it has one administrator with the right role and department owners who recognise the agents. The deliverable is a dated inventory with an owner, business purpose and decision for every shared or unmanaged item.
Bring in specialist help when the question changes from ownership to effective access. Tenant-wide tool restrictions, MCP server controls, Conditional Access for agents, Purview auditing, eDiscovery and DLP are listed by Microsoft as Agent 365 or E7/G7 capabilities (Microsoft Agent 365 service description, checked: 2026-10-05).
The first useful standard is modest: no shared agent without an owner, no uploaded knowledge without a reviewer and no employee departure without an agent check. That closes the most visible gap before a broader governance project begins.