The MCP server registered tools with `_tool` suffix (e.g. lint_scad_tool)
but mcp_servers.json groups listed bare names (lint_scad). This caused
_tool_list() to look for mcp_navi-3d_lint_scad which never existed in the
registry — the actual registered tool was mcp_navi-3d_lint_scad_tool.

Fix: explicitly set name= on @mcp.tool() decorators so MCP tool names
match the group whitelist in mcp_servers.json.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>