[BUG] www.anthropic.com is blocked from being retrieved when using the web search tool within Claude Code on home network with full access.

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

I was in plan mode and asked Claude Code to use the web search tool to fetch the latest guidance on effective writing of Skills. While it was able to retrieve content at docs.claude.com/ it was not able to fetch content at wwww.anthropic.com/ due to the below error.

<img width="1121" height="303" alt="Image" src="https://github.com/user-attachments/assets/28b57d29-a604-45f2-b55d-a0342121481b" />

What Should Happen?

Seeing as Anthropic owns Claude, this is one domain that should certainly not have been blocked while using the web search tool.

Error Messages/Logs

Steps to Reproduce

1. Start a Claude Code session with a starter prompt.
2. Enter plan mode to plan an implementation about a skill
3. Once Claude asks clarifying questions with an option to add text telling Claude to do something different from the other provided options, ask Claude to use the web search tool to reference Anthropic's latest guidance on writing effective skills.

Expected Behavior: Claude should be able to retrieve and parse official Claude Code documentation as well as engineering blogs on Anthropic's website for skills.

Actual Behavior: Retrieval of Claude Code docs on skills succeeded but the anthropic domain was blocked from being retrieved.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Opus 4.1 & Sonnet 4.5

Claude Code Version

2.0.55 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

<img width="1121" height="303" alt="Image" src="https://github.com/user-attachments/assets/bfcd0504-2015-4f58-a6cb-730f2dc8f20d" />