[BUG] MCP Tool view cannot handle " | None" types

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?

MCP Tool view cannot handle " | None" types, they are shown as "unknown" type. If I ask the model about parameters they the answer is correct, hence CLI is missing proper implementation to handle those.

What Should Happen?

Proper type shown.

Error Messages/Logs

/

Steps to Reproduce

MCP Tool view cannot handle " | None" types, they are shown as "unknown" type. Create a MCP server that returns " | None" Python type and view the Tool in Claude Code CLI.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.75

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_