MCP tool results with text content type are displayed as empty on Windows

Bug Description

On Windows, MCP tool calls that return content: [{type: "text", text: "..."}] responses are displayed as empty {"result":{"type":"text"}} to the model. The actual text field content is silently dropped, making all MCP tools that return text content effectively unusable.

Environment

• OS: Windows 11 Pro (10.0.26200)
• Shell: Git Bash (bash)
• Claude Code version: Latest (Desktop app, Windows)
• MCP Server: mcp-ssh-tool@1.3.1 (stdio transport)

Steps to Reproduce

1. Configure an MCP server in .mcp.json using stdio transport:

{
  "mcpServers": {
    "ssh-nas": {
      "command": "mcp-ssh-tool",
      "env": {
        "SSH_HOST": "192.168.0.101",
        "SSH_USER": "root",
        "SSH_PRIVATE_KEY": "C:\Users\user\.ssh\id_ed25519"
      }
    }
  }
}

1. Call any MCP tool (e.g. get_metrics, ssh_list_sessions, ssh_open_session)
2. All tool results show {"result":{"type":"text"}} with no actual content

Expected Behavior

The full text content should be visible, e.g.:

{"result": {"content": [{"type": "text", "text": "{\"sessions\":{\"created\":0,...}}"}]}}

Actual Behavior

All MCP tool results display as:

{"result": {"type": "text"}}

The text field is completely missing from the displayed result.

Verification

I manually tested the MCP server via stdio and confirmed it returns valid, complete responses:

printf '{"jsonrpc":"2.0","id":1,"method":"initialize",...}\n{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"get_metrics","arguments":{}}}\n' | mcp-ssh-tool 2>&1

The server returns full JSON-RPC responses with content: [{type: "text", text: "..."}] — but Claude Code strips the text field when presenting results to the model.

Additional Context

• The same MCP server works correctly in other MCP clients (e.g. OpenCode) using the same configuration but invoked via PowerShell instead of bash.
• This may be related to how Claude Code on Windows (using Git Bash) handles stdio communication with MCP server processes, possibly a character encoding or stream parsing issue specific to the bash shell environment.
• HTTP-transport MCP servers (like context7 and gh-grep) work fine — the issue appears specific to stdio-based MCP servers on Windows.