[BUG] Claude in Chrome: screenshot/debugger API fails with 'Cannot access a chrome-extension:// URL' even on clean profile with no other extensions

Bug Description

Screenshot and all debugger-based tools (screenshot, javascript_tool, left_click) fail with:

Error capturing screenshot: Cannot access a chrome-extension:// URL of different extension

The error message is misleading: the active tab is on a regular https:// URL (e.g., https://www.google.com), NOT a chrome-extension:// URL. The error suggests a cross-extension URL access issue, but no extension URL is involved — the debugger API simply fails to attach to any tab.

What Works vs. What Fails

| Tool | API Used | Status |
|------|----------|--------|
| tabs_context_mcp | Chrome tabs API | ✅ Works |
| tabs_create_mcp | Chrome tabs API | ✅ Works |
| navigate | Chrome tabs API | ✅ Works |
| read_page | Accessibility tree | ✅ Works |
| find | Accessibility tree | ✅ Works |
| screenshot | chrome.debugger API | ❌ Fails |
| javascript_tool | chrome.debugger API | ❌ Fails |
| left_click | chrome.debugger API | ❌ Not tested but likely fails |

All tools using the chrome.debugger API fail. All tools using the accessibility tree or tabs API work fine.

Steps to Reproduce

1. Create a brand new Chrome profile
2. Install only the Claude in Chrome extension
3. Close all other Chrome profiles and Chromium browsers
4. Restart Chrome completely (Cmd+Q and reopen)
5. Connect Claude Code to the extension
6. Navigate to any regular https:// URL (e.g., https://www.google.com)
7. Attempt computer(screenshot) → fails with the chrome-extension:// error even though the tab URL is https://

Troubleshooting Already Attempted

• ✅ Created a clean Chrome profile with only Claude in Chrome installed
• ✅ Disabled all other extensions
• ✅ Enabled "Allow JavaScript from Apple Events" (Chrome → View → Developer)
• ✅ Closed all other Chromium-based browsers
• ✅ Full Chrome restart (Cmd+Q)
• ✅ Created new tabs and navigated to fresh URLs
• ✅ Tested on multiple domains (google.com, smiles.com.br, voegol.com.br)
• ❌ None of the above resolved the issue

Environment

• OS: macOS (Darwin 25.3.0)
• Chrome: 146.0.7680.178
• Claude Code: 2.1.96

Related Issues

• #16239 — same error, but resolved by disabling extensions (not the case here)
• #29790 — same error on Anthropic websites