[BUG] WebFetchTool is broken

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?

Hi, WebFetchTool seems to be broken (I'm latest Claude Code version 1.0.115 + Vertex AI).
It seems to be a wrong "anthropic-beta" header value sent with WebFetchTool requests.
Also it sends claude-code-20250219 although i'm using the latest claude-sonnet-4@20250514 as the default model.

Here's the error i'm getting:

{
"type": "error",
"error": {
"type": "invalid_request_error",
"message": "Unexpected value(s) claude-code-20250219 for the anthropic-beta header. Please consult our documentation at docs.anthropic.com or try again without the header."
},
"request_id": "req_vrtx_011CTDg5623jbXZf4iXuJuuv"
}


What Should Happen?

invalid_request_error should not be the response.

Error Messages/Logs

> summarize this page: https://docs.claude.com/en/api/admin-api/organization/get-me

⏺ Fetch(https://docs.claude.com/en/api/admin-api/organization/get-me)
  ⎿  Received 1.4MB (200 OK)

⏺ Fetch(https://docs.anthropic.com/en/api/admin-api/organization/get-me)
  ⎿  Received 593 bytes (301 Moved Permanently)

⏺ Fetch(https://docs.claude.com/en/api/admin-api/organization/get-me)
  ⎿  Received 1.4MB (200 OK)

⏺ I'm unable to access the API documentation page due to a technical error. The URL appears to be for Claude's Admin API endpoint /organization/get-me, which would typically return information about the
  current organization, but I cannot retrieve the specific details without access to the documentation.

> show me the error you received and which endpoint returned it

⏺ The error I received was:

  {
    "type": "error",
    "error": {
      "type": "invalid_request_error",
      "message": "Unexpected value(s) `claude-code-20250219` for the `anthropic-beta` header. Please consult our documentation at docs.anthropic.com or try again without the header."
    },
    "request_id": "req_vrtx_011CTDg5623jbXZf4iXuJuuv"
  }

  This error was returned when I attempted to use the WebFetch tool to access the documentation page. The error indicates that the WebFetch tool is sending an anthropic-beta header with value
  claude-code-20250219 that the API doesn't recognize or accept.

  The error came from trying to fetch: https://docs.claude.com/en/api/admin-api/organization/get-me

Steps to Reproduce

1. Use the Vertex AI integration.
2. Try to fetch any URL from claude code (e.g. summarize this page: https://docs.claude.com/en/api/admin-api/organization/get-me)

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.0.115 (Claude Code)

Platform

Google Vertex AI

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_