resize_window
Adjust the browser window size for a specified tab to test responsive layouts at different viewport dimensions.
Instructions
Change the size of the Firefox window a tab lives in, so a layout can be checked at phone, tablet or desktop width and so screenshots taken afterwards come out at that geometry. width, height and tabId are all required; there is no implicit tab here. The real window is resized when Firefox allows that; headless runs and older builds refuse that, and the tab's viewport is stretched instead, which puts the page at the same size. The reply names whichever path ran and quotes the innerWidth x innerHeight the page ended up reporting - expect it to fall short of the numbers you asked for, since toolbars come out of the window box and the browser clamps sizes it thinks are too small. Only the tab you name is affected; the rest of the group keeps rendering as it was.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| tabId | Yes | The tab whose window gets resized; required, with nothing guessed for you. Take the id from tabs_context_mcp. If Firefox turns the window resize down, only this tab's viewport is changed and the other tabs are left alone. | |
| width | Yes | How wide to make the window, in pixels; must be positive. Browser chrome takes part of it, so the page area lands narrower than this - the reply says what the page actually measured. | |
| height | Yes | How tall to make the window, in pixels; must be positive. The tab strip and toolbar are subtracted from it, so the visible page is shorter; the reply quotes the innerHeight it settled on. |