VS Code mcp.json MCP servers not accessible to Claude Code extension tools

Summary

When Claude Code runs as a VS Code extension, it cannot access MCP servers configured in VS Code's user-level MCP settings file (%APPDATA%\Code\User\mcp.json).

Steps to reproduce

1. Add an MCP server to %APPDATA%\Code\User\mcp.json, e.g. Figma Desktop at http://127.0.0.1:3845/mcp or Figma cloud at https://mcp.figma.com/mcp
2. Open Claude Code VS Code extension
3. Ask Claude Code to use those MCP tools

Expected behavior

MCP servers registered in VS Code's mcp.json are available to Claude Code VS Code extension as internal tools — appearing in the tool registry and callable via the normal tool mechanism.

Actual behavior

Servers from mcp.json do not appear in Claude Code's tool registry. ListMcpResourcesTool only returns pre-bundled servers (claude-in-chrome, claude.ai Context7, sqz). The Figma servers are unreachable through any internal tool mechanism, even though they are running and reachable via raw HTTP.

Workaround

Raw HTTP calls to 127.0.0.1:3845/mcp work, but this is not the intended usage pattern.

Environment

• OS: Windows 11 Pro 10.0.22000
• Claude Code VS Code extension
• MCP servers affected: figma (HTTP, cloud https://mcp.figma.com/mcp), Figma Desktop (HTTP, local http://127.0.0.1:3845/mcp)

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Authored by Claude Code VS Code extension (claude-sonnet-4-6)