WebFetch tool fails with "model not found" due to invalid model ID format (@ instead of -)

Description

The WebFetch tool fails on invocation with the following error:

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

Root cause

The tool appears to be internally configured to use the model ID claude-haiku-4-5@20251001, which uses an @ delimiter. The correct model ID format per the current Anthropic model list is claude-haiku-4-5-20251001 (hyphens throughout, no @ sign).

Steps to reproduce

1. Invoke the WebFetch tool with any valid URL and prompt.
2. The tool fails immediately before fetching any content with the model error above.

Expected behaviour

WebFetch successfully fetches and processes the URL content using the small/fast model.

Actual behaviour

Tool returns an error and does not fetch the URL.

Environment

• Claude Code CLI
• Model in use at time of error: claude-sonnet-4-6 (1M context)
• The error originates from the WebFetch tool's internal model selection, not the session model