Run script

preview_eval

Group: Preview
Turned on by: Its own switch on the Tools page of Conversation settings.
Approval: Reviewed: writes and open-ended actions ask for approval unless the security level or an earlier “Always allow” covers them.
Profile key: tool.preview_eval.description

Runs a JavaScript expression in the conversation's preview page and returns its result as JSON.

The model also uses it to navigate, reload, hover and press keys, since no other tool does those. A returned promise is awaited. Changes it makes to the page last only until the next reload.

When it asks you

Asks at Manual and Accept edits, because the script can do anything the page itself can; Always allow is not offered. If you have been using the page yourself, you hand it back first in the pane; on a signed-in page, that takeover needs your approval at every security level. See Browser and preview.

Limits

The call stops waiting for a result after 15 seconds.

Parameters

Parameter	Type	Details
`expression` required Expression	string	JavaScript expression to evaluate in the page context. Return values are serialized as JSON.
`serverId` Server ID	string	Server ID