/mcp list doesn't show zen MCP tools that are loaded and functional

Description

There's a discrepancy between /mcp list and /context commands regarding zen MCP server tools visibility.

Current Behavior

• /mcp list returns empty or doesn't show zen MCP server
• /context shows zen MCP tools are loaded (mcp__zen__chat, mcp__zen__thinkdeep, etc.)
• Zen tools work correctly when invoked (tested with mcp__zen__chat)

Expected Behavior

/mcp list should display all available MCP servers including zen, consistent with what /context shows.

Steps to Reproduce

1. Run /mcp list command - returns empty/no content
2. Run /context command - shows zen tools loaded with token counts:

``
└ mcp__zen__chat (zen): 2.5k tokens
└ mcp__zen__thinkdeep (zen): 3.0k tokens
└ mcp__zen__planner (zen): 2.6k tokens
[... and more zen tools]
``

1. Use a zen tool like mcp__zen__chat - works correctly

Evidence

• Zen tools successfully used to interact with Gemini 2.5 Pro and GPT o3-mini models
• Tools are auto-approved and functional
• Only the listing/discovery is inconsistent

Impact

Users cannot discover available zen MCP tools through /mcp list, leading to confusion about what tools are available.

Environment

• Claude Code (CLI version)
• Platform: darwin
• Multiple MCP servers configured (github, confluence, zen, roy-jira, slack, jira-hackdonalds)