Claudeにブラウザを操作させるなら内蔵ブラウザかChrome拡張を選ぶ

"Claude now has a browser built into Claude Cowork on the desktop app. When a task needs to use a website, a browser opens in the side panel and Claude navigates webpages, reads them, clicks, and types." ／ "No extension, no setup, and nothing shared from your own browser unless you choose to." ／ "Until now, giving Claude the ability to use the web in Cowork meant giving it access to your browser through the" — Cowork 内蔵ブラウザ発表の冒頭より

"Claude in Chrome is now generally available on every paid Claude plan." ／ "Claude can now also take actions autonomously in the browser, instead of needing approval for every one." ／ "(You can switch this off in your settings if you'd prefer to continue to approve Claude's actions manually.)" — Claude in Chrome 一般提供発表の冒頭より

"The built-in browser is separate from your own. Claude never sees your tabs, bookmarks, or passwords." ／ "Banking, email, and single sign-on sites are left out unless you choose to include them." ／ "you can bring your logins over site by site, from Chrome, Edge, or Firefox on macOS and from Firefox on Windows and Linux." — 内蔵ブラウザの分離に関する節より

"such as internal dashboards, legacy systems, and vendor portals. Claude in Chrome lets Claude access those." ／ "using your existing logins." — Claude in Chrome の位置づけを述べた段落より

"Claude in Chrome is for the page you already have open, with the accounts you're already signed in to, such as updating your CRM, working through your inbox, or editing the doc in front of you." — 2つの使い分けを説明した節より

"The built-in browser is for handing web tasks to Claude while you keep working: gathering research for a report" ／ "or collecting this month's invoices from a vendor portal." ／ "From the web or your phone, Claude can still drive it as long as your desktop app is open and online." — 2つの使い分けを説明した節より

"We train probes to scan those results for potential prompt injections." ／ "A classifier reviews actions Claude is about to take, such as navigating to a new website or entering text into a page, and checks them against what you originally asked for." ／ "We train Claude against a growing library of prompt injection attacks, sourced from our internal automated attackers, external red-teamers, and real-world monitoring." ／ "When a new attack succeeds against a current model, it's added to the library" — 安全対策を説明した節より

"attacks that reached the model succeeded against Opus 4.5 17.6% of the time and against Opus 5 3.8% of the time, before any additional safeguards" ／ "With the strongest safeguards available in November 2025, attacks against Opus 4.5 running with probes succeeded 16.7% of the time." ／ "We saw a 0.3% attack success rate against Fable 5." ／ "when running with probes and the safety classifier, no attacks succeeded against Claude Sonnet 5, Claude Opus 5, or Claude Mythos 5." ／ "We have manually verified that all successful breaks are in low-severity scenarios and are working to mitigate them." ／ "In some cases, the actions Claude takes result in it never encountering the malicious instructions." — 評価結果を報告した節より

"Those measures meaningfully reduce the risk but can't eliminate it, so we recommend starting on sites you trust." — 安全対策の節より

"The built-in browser is rolling out over the coming week to Pro, Max, and Team plans in the Claude desktop app on macOS, Windows, and Linux (in beta)." ／ "Once it reaches you, it's on by default" ／ "On Enterprise plans, it's available now and admins can manage it in Organization settings → Cowork → Built-in browser." — 提供状況を説明した節より

"On Enterprise plans, admins can manage it in Organization Settings and limit it to approved domains." — 提供状況の節より

"Switch anytime in Settings → Cowork → Preferred browser." — デフォルトのブラウザの切り替えを説明した箇所より