MCP tool call parameters display characters vertically (one character per line)

Description

When Claude Code displays MCP tool call parameters in the terminal UI, the characters are rendered vertically (one character per line) instead of horizontally on a single line.

Steps to Reproduce

1. Configure an MCP server in .mcp.json that has a tool with parameters
2. Call the MCP tool with parameters (e.g., response_format: "markdown")
3. Observe the tool call display in the terminal

Expected Behavior

Tool call parameters should display horizontally:

my_mcp_tool {"params": {"response_format": "markdown"}}

Actual Behavior

Each character of the parameter JSON is displayed on a separate line:

my_mcp_tool {
"
p
a
r
a
m
s
"
:
 
{
"
r
e
s
p
o
n
s
e
_
f
o
r
m
a
t
"
:
 
"
m
a
r
k
d
o
w
n
"
}
}

Environment

• OS: macOS Darwin 25.1.0
• Terminal: VS Code integrated terminal

Additional Context

This appears to be a rendering issue in how Claude Code displays MCP tool invocations. The tool itself works correctly and returns expected results - only the display is affected.