[BUG] VSCode Extension: Responses Not Rendering Due to MCP Server Error -32601

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?

The Claude Code VSCode extension (v2.0.46) successfully authenticates and sends requests, but responses are not displayed in the UI. The extension gets stuck on the "thinking" animation (showing words like "Scheming", "Crunching", etc.) but never renders Claude's response.

What Should Happen?

Expected Behavior

• User message appears
• "Thinking" animation shows briefly
• Claude's response is rendered in the chat UI

Error Messages/Logs

### VSCode Extension Log

2025-11-19 10:53:23.009 [info] OAuth tokens found in secure storage
2025-11-19 10:53:23.009 [info] Auth status: method=claudeai
...
2025-11-19 10:53:27.072 [info] From claude: 2025-11-19T15:53:27.060Z [ERROR] MCP server "claude-vscode" Failed to fetch tools: MCP error -32601: Method not found
...
2025-11-19 10:53:30.028 [info] From claude: 2025-11-19T15:53:29.295Z [DEBUG] Stream started - received first chunk


### CLI Debug Log

2025-11-19T15:53:29.295Z [DEBUG] Stream started - received first chunk
2025-11-19T15:54:55.862Z [ERROR] Error: Error: Language not supported while highlighting code, falling back to markdown:

Steps to Reproduce

1. Open VSCode with Claude Code extension installed
2. Open Claude Code panel in VSCode
3. Send any message (e.g., "hello")
4. Observe the behavior

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.46

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

_No response_