browser_eval
Automate web application testing with Playwright browser automation. Load and interact with pages in real browsers to detect runtime errors, hydration issues, and client-side problems.
Instructions
Automate and test web applications using Playwright browser automation. This tool connects to playwright-mcp server and provides access to all Playwright capabilities.
CRITICAL FOR PAGE VERIFICATION: When verifying pages in Next.js projects (especially during upgrades or testing), you MUST use browser automation to load pages in a real browser instead of curl or simple HTTP requests. This is because:
Browser automation actually renders the page and executes JavaScript (curl only fetches HTML)
Detects runtime errors, hydration issues, and client-side problems that curl cannot catch
Verifies the full user experience, not just HTTP status codes
Captures browser console errors and warnings via console_messages action
IMPORTANT FOR NEXT.JS PROJECTS: If working with a Next.js application, PRIORITIZE using the 'nextjs_index' and 'nextjs_call' tools instead of browser console log forwarding. Next.js has built-in MCP integration that provides superior error reporting, build diagnostics, and runtime information directly from the Next.js dev server. Only use browser_eval's console_messages action as a fallback when these Next.js tools are not available or when you specifically need to test client-side browser behavior that Next.js runtime cannot capture.
Available actions:
start: Start browser automation (automatically installs if needed). Verbose logging is always enabled.
navigate: Navigate to a URL
click: Click on an element
type: Type text into an element
fill_form: Fill multiple form fields at once
evaluate: Execute JavaScript in browser context
screenshot: Take a screenshot of the page
console_messages: Get browser console messages (for Next.js, prefer nextjs_index/nextjs_call tools instead)
close: Close the browser
drag: Perform drag and drop
upload_file: Upload files
list_tools: List all available browser automation tools from the server
Note: The playwright-mcp server will be automatically installed if not present.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| action | No | The action to perform using browser automation | |
| browser | No | ||
| headless | No | ||
| url | No | ||
| element | No | ||
| ref | No | ||
| doubleClick | No | ||
| button | No | ||
| modifiers | No | ||
| text | No | ||
| fields | No | ||
| script | No | ||
| fullPage | No | ||
| errorsOnly | No | ||
| startElement | No | ||
| startRef | No | ||
| endElement | No | ||
| endRef | No | ||
| files | No |