[BUG] Gmail MCP: batch_modify_emails rejects array parameters as strings

Description

The gmail_batch_modify_emails tool (via mcp__claude_ai_Gmail) rejects array parameters with Expected array, received string for messageIds, addLabelIds, and removeLabelIds. The tool schema specifies arrays, but MCP serialization appears to send them as strings.

Steps to Reproduce

1. Use the Gmail MCP batch_modify_emails tool
2. Pass messageIds, addLabelIds, or removeLabelIds as arrays (e.g., ["msg123", "msg456"])
3. Tool returns validation error: Expected array, received string

Expected Behavior

Array parameters should be accepted and processed correctly.

Actual Behavior

All array parameters are rejected with type validation errors, making the tool unusable.

Workaround

Direct Gmail REST API calls via Node.js https module.

Environment

• Claude Code on Linux (Ubuntu 24.04)
• First observed: 2026-02-20
• Still present as of 2026-03-09