Web Search Cn

Web Search (China)

Overview

Search the web when the built-in WebSearch won't do — its backend is US-only and covers Chinese content poorly. Drive real search engines through the Playwright MCP instead: Baidu for China-local content (Chinese query, as-is), Google for technical/international content (Chinese query auto-translated to English first). No API keys, no new deps.

Network constraints: Bing (all domains) is blocked on the user's company network — never use Bing. If Google is unreachable (company network may block it), fall back to Sogou (国内可达, no key), then Baidu for the technical query as a last resort. Baidu is always reachable.

When to Use

• User asks to search and the content lives on the Chinese internet.
• WebSearch gives US-centric or empty results for a China-related query.
• Need domestic companies, policies, Chinese community content, local weather/events.
• Technical search where English web has better coverage (libs, frameworks, papers, APIs).

Engine Selection

When unsure, run BOTH and merge — the cost is one extra navigate + snapshot.

Workflow

1. Classify intent (table above). If unclear → search both.
2. Build the URL (URL-encode the query):
   • Baidu: https://www.baidu.com/s?wd=<encoded Chinese query>
   • Google: https://www.google.com/search?q=<encoded English query>&hl=en-US
   • Sogou fallback (if Google unreachable): https://www.sogou.com/web?query=<encoded English or Chinese query>
3. browser_navigate to the URL. Detect block: if document.title is empty / generic / an error page, or looksBlocked (see Reachability check below), treat as unreachable and fall through.
4. Run the extractor via browser_evaluate — pick by engine (see Extraction below) → ~8 results as compact JSON. Falls back to browser_snapshot only if the extractor returns empty.
5. For a result needing full content: WebFetch the URL, or browser_navigate to it + browser_snapshot.
6. Fallback chain for technical/international queries: Google → Sogou → Baidu (with the English query; Baidu's English-tech coverage is weak but non-zero). Stop at the first engine that returns ≥3 results. China-local queries stay on Baidu (always reachable).
7. Synthesize results, cite titles + URLs.

Reachability check

After browser_navigate, run this before extracting. If blocked is true (or results < 3), fall through to the next engine in the chain.

() => ({
  title: document.title,
  h3: document.querySelectorAll('h3').length,
  externalLinks: [...document.querySelectorAll('a[href^="http"]')].filter(a => !/baidu\.com|google\.|sogou\.com|bing\.com/.test(a.host)).length,
  blocked: /can't be reached|err_|refused|timed out|无法访问|连接被重置|forbidden|ERR_/.test((document.body && document.body.innerText) || '') || !document.title || document.title.length < 3
})

Extraction

Pick the extractor by current engine (based on the URL you navigated to). Both verified working.

Baidu + Google (unified h3 extractor)

Baidu: link is inside h3 (h3 a). Google: link is an ancestor of h3 (h3.closest('a')). The || covers both. Skips Baidu ads (baidu.php) and Google self-links. Returns {title, url, snippet}.

() => {
  const out = [];
  document.querySelectorAll('h3').forEach(h3 => {
    const a = h3.querySelector('a') || h3.closest('a');
    if (!a) return;
    const title = (h3.innerText || '').trim();
    if (!title) return;
    let box = h3.parentElement;
    for (let i = 0; i < 4 && box; i++) { if ((box.innerText||'').length > title.length + 20) break; box = box.parentElement; }
    const snippet = box ? (box.innerText || '').replace(title, '').trim().slice(0, 160) : '';
    out.push({ title: title.slice(0, 120), url: a.href, snippet });
  });
  const seen = new Set(), res = [];
  for (const r of out) {
    if (!r.title || !r.url || seen.has(r.url)) continue;
    if (/baidu\.php|google\.com\/search|^https:\/\/www\.google\./.test(r.url)) continue;
    seen.add(r.url); res.push(r);
    if (res.length >= 8) break;
  }
  return res;
}

Sogou fallback extractor (title + url only)

Sogou result blocks (div.vrwrap) mostly lack h3, and the title link's ancestor container holds the whole numbered result list — so snippets can't be cleanly extracted. Take title + url only; WebFetch for content. Title text includes a trailing source line (e.g. \n博客园); keep only the first line.

() => {
  const links = [...document.querySelectorAll('a[href^="http"]')];
  const seen = new Set(), res = [];
  for (const a of links) {
    const raw = (a.innerText || '').trim();
    if (raw.length < 8) continue;
    if (/sogou\.com|yuanbao\.tencent|tencent\.com\/evt|qq\.com\/evt/.test(a.href)) continue;
    const title = raw.split('\n').map(s => s.trim()).filter(Boolean)[0] || raw;
    if (!title || seen.has(a.href)) continue;
    seen.add(a.href);
    res.push({ title: title.replace(/^\d+\.\s*/, '').slice(0, 100), url: a.href, snippet: '' });
    if (res.length >= 8) break;
  }
  return res;
}

• Baidu result URLs are redirect-wrapped: baidu.com/link?url= is organic, baidu.php?url= is an ad (ads are filtered). Following a link?url= URL via browser_navigate lands on the real page.
• Sogou URLs are direct (no redirect wrap) for non-WeChat sources; WeChat (mp.weixin.qq.com) links carry query params but work.
• Google/Sogou snippets are weak — WebFetch the URL for full content.

Query Translation (Google path)

Translate the Chinese query to a concise keyword query in English — not a full sentence. Drop filler. Keep proper nouns.

• Python asyncio 怎么做并发 → python asyncio concurrency
• 华为鸿蒙系统架构 → huawei harmonyos architecture

Cleanup

After the search session, close the browser and remove Playwright temp files (CLAUDE.md browser-cleanup rule):

rm -f crg-*.png page-*.png && rm -rf .playwright-mcp

Common Mistakes

• Using Bing — blocked on the user's company network (all bing domains). Never use Bing as a fallback; use Sogou then Baidu.
• Sending a China-local query to Google translated — "华为Mate70国内首发渠道" has no English-web coverage; keep it on Baidu.
• Sending a technical query to Baidu in Chinese — English docs/Stack Overflow/GitHub have better coverage; translate and use Google (fall back to Sogou if Google is blocked).
• Skipping translation for Google — a Chinese query on Google.com returns mostly Chinese-translated pages and misses the rich English web.
• Forgetting to URL-encode — spaces/CJK in the URL can break navigation; encode the query.
• Expecting Sogou snippets — Sogou extractor returns title+url only; WebFetch for content instead of trusting a snippet.
• Leaving the browser open — cleanup per CLAUDE.md.