resize

resize

Resize the browser window.

MCP tool	resize
HTTP	POST /browser/resize

Use this when layout matters and the browser was opened for you, or when you need a different size partway through. The headless default is small and varies between Grid nodes, so set it explicitly before judging anything visual.

The new size sticks to the session, so a browser the Grid reaps and reopens comes back the size you last set rather than the size it was opened at.

Parameters

Name	Type	Required	Default	Notes
width	integer	no	—
height	integer	no	—
session_id	string	yes over HTTP	—	The session_id returned by /browser/open. Required here.

Returns

Field	Type	Notes
width	integer	Window width now in effect.
height	integer	Window height now in effect.
url	string	Current URL after the action.
title	string	Page title after the action.

Errors

Status	Means
400	The request cannot succeed as sent — a missing field, a value that was rejected, or a locator that matched nothing before the wait ran out. Do not retry it unchanged.
401	Missing or wrong bearer token.
404	No such browser session. It ended, the Grid reaped it, or the id was never real. Open a new one and retry.
500	Something failed that this server did not expect.
503	The Grid could not serve this — unreachable, or no free slot for a new browser. Worth retrying after a wait.

Over MCP the same failures arrive as a tool error.

Example

MCP

resize()

HTTP

curl -X POST $SELENIUM_FLOW/browser/resize \
  -H "Authorization: Bearer $TOKEN" \
  -H 'Content-Type: application/json' \
  -d '{
    "session_id": "…"
  }'

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