[BUG] SubAgent MCP tool calls(configured via mcpServers yaml frontmatter in subagent.md) show as blank line in Ctrl+O view

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?

SubAgent MCP tool calls(configured via mcpServers yaml frontmatter in subagent.md) show as blank line in Ctrl+O view

What Should Happen?

It should display normally as global mcp server tool calls

└ mcp-xxxx - xxx (MCP)(param: xxx)

Error Messages/Logs

Just blank line in Ctrl+O view

└

Steps to Reproduce

1. Remove a mcp server from project config(.mcp.json)
2. Add this mcp server to subagent.md frontmatter like below

---
name: my-new-subagent
description: ***
tools: ***
model: inherit
color: yellow
mcpServers:
  - my-mcp-server:
       type: "stdio"
       command: "python"
       args: ["***"]
---

1. Create a new session, and ask claude to do something with this subagent
2. It appears that subagent can call tools in this mcp server normally, but tool calls shows as blank line in Ctrl+O view.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.55

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_