Browsing

Browsing

ALWAYS use a subagent for browser tasks. Never call browser tools directly in main context — the snapshots consume thousands of tokens per page.

Task tool config:
  subagent_type: general-purpose
  model: haiku

The subagent does all navigation and interaction, then returns a concise summary.

Sessions persist per project. All tool calls in a conversation share one browser instance.

Headed Browser

When the user needs to see or interact with the browser (OAuth, CAPTCHAs, login), open a headed browser sharing the same profile. Close the headless browser first with browser_close, then launch via Bash with run_in_background: true:

const pw = require('<playwright-path>');
(async () => {
  const ctx = await pw.chromium.launchPersistentContext('<profile-path>', {
    headless: false, channel: 'chrome',
    args: ['--disable-session-crashed-bubble', '--hide-crash-restore-bubble']
  });
  const page = ctx.pages()[0] || await ctx.newPage();
  await page.goto('<url>');
  await page.waitForEvent('close').catch(() => {});
  await ctx.close();
})();

To find the values:

• playwright-path: find ~/.npm/_npx -path '*/@playwright/mcp' -type d → sibling playwright package
• profile-path: ~/Library/Caches/ms-playwright/mcp-chrome-<hash> where hash = first 7 chars of SHA-256 of project root path

The script waits in the background until the user closes the window, then cleans up so headless can resume.

Tips

• browser_fill_form for multiple fields, not browser_type per field
• Screenshots to check visuals (saves tokens), snapshots when you need refs
• Cache refs from first snapshot, reuse for subsequent interactions
• On token limit errors, output is auto-saved to a file — use Bash to extract what you need

Workflows

Check UI: Navigate → screenshot → analyze

Submit form: Snapshot (get refs) → browser_fill_form → click submit → screenshot (verify)

Debug visuals: Full-page screenshot → element screenshot → console messages

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