A service account is a non-human login that software uses, usually shared and long lived. An agent identity is a distinct identity for one AI agent, tied to an owner, a purpose and a scoped set of permissions. They overlap on credentials. They differ on who is acting and who answers for it.
Why compare them at all?
Teams ship agents quickly, and the fastest way to give an agent access is to hand it an existing service account. That works on day one and causes trouble later, because the account no longer says which agent did what.
OWASP's Non-Human Identities Top 10 for 2025 names the usual failures of service accounts: improper offboarding, secret leakage, overprivileged identities and long-lived secrets. Agents inherit all of those risks and add their own.
What is a service account good at?
It suits software that does one predictable job. A nightly export, a CI runner pulling from a registry, a service calling a database. The behavior is fixed, so a fixed credential with fixed rights is a fair match.
Mature setups reduce the risk further with short-lived identity. SPIFFE defines short-lived cryptographic identity documents for workloads, so services authenticate without a static secret sitting in config.
Where does an agent differ?
An agent decides at run time what to do. Two runs of the same agent can call different tools and touch different data. That changes the control question. For a service account you ask "what can this credential do?" For an agent you also ask "what did it choose to do, for whom, and who approved the scope?"
An agent often acts for a person. RFC 8693 separates two ideas that matter here. With impersonation, the agent is treated as the user. With delegation, the agent keeps its own identity and acts on the user's behalf, so the record shows both. Delegation is the better fit for agents, because the audit trail keeps the agent visible.
Where do they overlap?
Both are non-human. Both need an owner, a rotation or expiry plan, least privilege and an offboarding step. An agent identity can even be implemented on top of a service account or a workload identity. The difference is in the metadata and the controls around it, not the credential type.
A constructed example
Say a support team deploys a triage agent that reads tickets and drafts replies. Version one uses the existing helpdesk service account, which can also close accounts. A month later nobody can say whether a closure came from the agent, a script or a person. The fix is a separate identity for the agent, an owner on record, rights limited to read tickets and write drafts, and a log that shows which agent took each action.
When do you need each?
Use a service account, ideally short lived and per service, for fixed automation. Use an agent identity when software chooses its own actions, calls tools, or acts for people. Many estates need both.
What to do
- Inventory your non-human identities and mark which ones back an agent.
- Give each agent its own identity and a named human owner.
- Scope permissions to the tools the agent needs, and review them on a schedule.
- Prefer short-lived credentials over static keys.
- Use delegation semantics so logs show agent and user.
- Define offboarding: who disables the identity when the agent is retired.
Where Safeguard fits
Safeguard offers agent identity, which tracks which agent holds what access at what level, and an MCP Guardrail that proxies MCP servers so tool calls can be checked against policy. These are generally available. They sit alongside your identity provider, not in place of it.
Quick check
Can an agent just use a service account?
It can, but you lose attribution. If several agents or scripts share one account, you cannot tell them apart in logs or revoke one without breaking the rest.
Is an agent identity a new kind of credential?
Usually not. It is often an existing credential type with an owner, scope and audit record attached to one specific agent.
Sources
Last reviewed: 18 October 2026.
