browser_tab_run

Execute JavaScript code in the browser tab. The code runs as an async function body.

CRITICAL RULES:

• MUST call browser_tab_open before browser_tab_run

• ALWAYS await async tab methods

• tab.observe() and tab.goto() invalidate previous element refs

• Default to tab.observe() for page state; screenshot only when appearance matters

• For reading static content (articles, docs, JSON, PDFs), prefer webfetch — browser is for JS execution, auth, interactive actions

Available variables in scope:

• tab — TabApi object: tab.url(): string (sync) tab.title(): Promise tab.goto(url, { waitUntil? }) waitUntil: 'load' | 'domcontentloaded' | 'networkidle' tab.click(selector) CSS, "text/...", "xpath/...", "aria-ref=..." tab.type(selector, text) tab.fill(selector, value) clear + type into input tab.press(key, { selector? }) e.g. 'Enter', 'Escape' tab.hover(selector) tab.scroll(deltaX, deltaY) tab.scrollIntoView(selector) tab.screenshot({ fullPage?, selector? }) returns base64 PNG tab.evaluate(fn, ...args) raw JS in page context tab.observe() accessibility tree: { elements: [{ id, role, name, value, focused }] } tab.ariaSnapshot() Playwright-format YAML tree with [ref=eN] ids, [cursor=pointer] for clickables tab.id(n) ElementHandleActions from observe() id tab.ref("e5") ElementHandleActions from ariaSnapshot() ref tab.waitForSelector(selector, { timeout?, visible?, hidden? }) tab.waitForUrl(pattern, { timeout? }) string substring or RegExp tab.waitForResponse(pattern, { timeout? }) string, RegExp, or (res) => boolean tab.waitForNavigation({ waitUntil?, timeout? }) tab.select(selector, ...values) option(s) tab.drag(from, to) selector or { x, y } point tab.extract(format?) 'markdown' | 'text' | omitted (returns HTML) tab.uploadFile(selector, ...filePaths) file input

ElementHandleActions: { click, type, fill, hover, focus, screenshot, evaluate, scrollIntoView }

• display(value) — emit structured output (NOT a tab.* method)

• wait(ms) — delay (NOT a tab.* method; use bare wait(2000), not tab.wait(...))

• assert(cond, msg?) — guard (NOT a tab.* method)

Selectors: CSS by default, "text/Sign in" for visible text, "xpath/...", "aria-ref=e5" from ariaSnapshot.

Single-expression code auto-returns its value (no explicit 'return' needed). Use display() for intermediate values.