WebSearch tool fails with model-access error on every call

Description

The built-in WebSearch tool consistently fails with a model-access error, on every invocation, regardless of query content.

Error

There's an issue with the selected model (cc/claude-haiku-4-5-20251001). It may not exist or you may not have access to it.

Steps to reproduce

1. In a Claude Code session, have Claude call the WebSearch tool with any query.
2. The call fails immediately with the error above — no search is ever performed.

Environment

• Claude Code version: 2.1.220
• OS: macOS 27.0 (BuildVersion 26A5388g), Darwin 27.0.0
• Observed: 2026-07-26

Notes

• Reproducible across the active session model: tested with both claude-sonnet-5 and claude-haiku-4-5-20251001 as the main conversation model — same error both times. This suggests the failure is tied to a fixed internal model that WebSearch depends on for processing results, not to whichever model the user has selected for the session.
• Not a general network/sandbox issue: browser-based navigation to a search engine (via the Claude Browser pane / mcp__Claude_Browser__* tools, e.g. https://duckduckgo.com/html/?q=...) works fine and returns real results. Only the native WebSearch tool call fails.
• Retried multiple times across a single long-running session (several attempts, minutes apart) — error is consistent, not a transient blip.

Impact

Any workflow relying on WebSearch for up-to-date information currently degrades silently to a hard error, forcing a manual workaround via the browser tools.