[BUG] Bash tool fails with syntax error when multiple command substitutions $(...) are used

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?

The Bash tool incorrectly escapes command substitutions when there are multiple $(...) in a single tool call, causing syntax errors. The tool converts $(...) to \$ ( ... ) which breaks bash syntax.

What Should Happen?

The command should execute normally, as it does in a regular bash terminal.

Environment:

• Platform: Linux
• OS: Linux 6.12.57+deb13-amd64
• Claude Code version: [your version]

Workaround:

Use only ONE command substitution per Bash tool call:
# Works - single substitution
TOKEN=$(cat some/file)
echo "Token: $TOKEN"

Or use inline substitution in a single command:
curl https://example.com -H "Auth: $(cat token/file)"

Error Messages/Logs

Error:
  /bin/bash: eval: line 1: syntax error near unexpected token `('
  /bin/bash: eval: line 1: `TOKEN=\$ ( cat some/file ) PORT\=\$ ( grep pattern file < /dev/null | cut -f2 ) echo 'Token: ' echo 'Port: ''

  Notice the command substitutions are incorrectly escaped as \$ ( ... ).

Steps to Reproduce

1. Use the Bash tool with multiple command substitutions:

TOKEN=$(cat some/file)
PORT=$(grep pattern file | cut -f2)
echo "Token: $TOKEN"
echo "Port: $PORT"

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.0.55 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_