Yes. Give an agent its routine tools permanently, and give risky tools only for a defined task or a short window that expires on its own. Just in time grants shrink the period in which a stolen token or a hijacked agent can do harm, and they leave a clear record of who approved what.
Standing access versus time boxed access
Standing access is easy and quietly dangerous. A write credential issued for a one week migration is still live a year later because nobody owns its removal. A time boxed grant carries its own end date, so doing nothing is the safe outcome.
OAuth already supports this idea. RFC 6749 describes scope as a space delimited list that the authorization server defines, and says the server may fully or partially ignore the scope a client requests and must tell the client what it granted. That makes narrower, shorter grants a normal part of the protocol, not a workaround.
Which tools deserve a time box
| Tool class | Standing access | Time boxed grant |
|---|---|---|
| Read on non sensitive data | Fine | Not needed |
| Read on sensitive data | Scoped, reviewed | For one-off analysis |
| Write on production | Avoid | Yes, per change |
| Delete | Avoid | Yes, with named approver |
| Send or pay | Avoid | Yes, with limits |
Steps to run time boxed grants
- Define the request: agent, tool, scope, reason, and the task or ticket it supports.
- Approve with a named person who is not the requester. Record the decision.
- Issue a credential that expires at the end of the window. Short lifetimes beat promises to revoke later.
- Log every call made under the grant with the grant ID.
- Let it lapse. Extending needs a fresh approval, not a quiet renewal.
- After expiry, check that the credential no longer works. Test it once.
Pitfalls
Do not let the approval prompt become a rubber stamp. Show the approver the tool, the scope and the end time. Do not size the window by convenience; size it by the task. And do not issue the same long lived token under a new name.
Break glass
Outages happen. Define an emergency path with automatic expiry and after the fact review, and keep it rare enough that every use gets read.
Safeguard offers MCP Guardrail and agent identity for applying this kind of policy to agent tool calls, and you can run a free scan of your own repositories at gold.safeguard.sh/scan. Autonomous fix pull requests are off by default, and every category starts on Manual.
Try it yourself
Click through it at your own pace, or open it full screen. Watch which settings decide what the connected assistant can reach.
Quick check
How long should a time boxed grant last?
As long as the task needs and no longer. Hours for a change, days for a project. Extend by new approval.
Does this slow agents down?
Only for risky tools. Routine read tools stay available, so most work is unaffected.
Sources
Last reviewed: 19 October 2026.
