[BUG] MCP tools fail with "tool_use ids must be unique" when run via launchd

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?

Environment:

• Claude Code version: 2.1.19
• macOS
• Running via launchd scheduled task

What happens:
When Claude Code is run via launchd with MCP servers loaded (using --mcp-config), any attempt to use MCP tools fails
with:
API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.1.content.1: tool_use ids
must be unique"}}

What works:

• Running the same command interactively in Terminal
• Running via launchd WITHOUT using MCP tools
• Loading MCP config via launchd (tools appear) but not calling them

What Should Happen?

Expected: MCP tools should work the same via launchd as they do interactively.

Error Messages/Logs

Steps to Reproduce

Reproduction:

1. Create a launchd plist that runs claude with --mcp-config pointing to valid MCP servers
2. Use -p with a prompt that asks Claude to use an MCP tool
3. Observe the tool_use ID collision error

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.19

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_