This MCP server has 14 well-named tools with consistent verb-noun patterns (list_, search_, get_, send_, mark_, move_, flag_, create_, delete_, reply_, forward_). Input schemas are present and mostly complete with type definitions and descriptions. However, output schemas are entirely absent from the code provided, the tool creators return structured objects but no formal output schema documentation is visible. Descriptions are present but generic (avg ~60 chars), lacking LLM-optimized context about WHEN to use each tool or how they chain together. Parameters have types and descriptions, but some lack enum constraints (e.g., 'color' enum in flag_message is present but several tools accept free-form strings). Error handling exists (security/OperationLogger) but recovery guidance is not visible in tool definitions. Security is a strength, the logger is threaded through every operation, and no secrets appear in parameters. Overall, this is a solid but incomplete implementation: good naming and basic structure, but missing output documentation and richer descriptions.

• Document output schemas for all 14 tools. Example: list_mailboxes should return {mailboxes: [{name: string, unread_count: int, account: string}], total_count: int}. Make response structures explicit so LLMs can parse results correctly.
• Expand tool descriptions from single lines to 50-150 chars with context. Example: 'Search for messages by sender, subject, or read status. Call this first to retrieve message IDs for use with get_message, mark_as_read, or delete_messages.' Include discovery hints.
• Add parameter descriptions inline. For search_messages limit param: 'Maximum results to return (1-1000, default 50). Larger limits may slow searches on large mailboxes.'
• Integrate enum values into descriptions, not just schema. For flag_message: 'Color flag to set (must be one of: none, orange, red, yellow, blue, green, purple, gray).'
• Add error recovery guidance to descriptions of write/destructive tools. Example for delete_messages: 'Irreversible. Use permanent=false first to move to trash, then verify before setting permanent=true. If deletion fails, check that message_ids exist via search_messages.'
• Implement a dry-run mode for delete_messages (add 'dry_run' boolean param). Or add a 'confirm_delete' tool that the LLM must call before permanent deletion.
• Clarify tool-chaining IDs. Ensure search_messages returns message_id in a consistent format that delete_messages, mark_as_read, etc. all accept. Document in each tool description which prior tools return compatible IDs.
• Add dependency hints to get_message, mark_as_read, delete_messages, reply_to_message, forward_message: 'Requires message_id from search_messages or list from a prior call.'

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry