API Error: 400 due to tool use concurrency issues when running Bash commands

Description

Encountered a 400 error with message "tool use concurrency issues" when executing a simple bash command. The command itself executed successfully, but the API returned an error afterward.

Steps to Reproduce

1. Run a simple bash command (e.g., echo "__tool_test__")
2. Command output appears correctly
3. API error 400 is thrown

Observed Behavior

IN
echo "__tool_test__"

OUT
__tool_test__
API Error: 400 due to tool use concurrency issues.

Expected Behavior

Command should complete without API error since the bash execution succeeded.

Environment

• OS: macOS (Darwin 25.2.0)
• Model: claude-opus-4-5-20251101
• Claude Code version: 2.1.19

Additional Context

Error appears to be related to internal tool call handling/timing rather than the actual command execution.