This MCP server demonstrates solid foundational quality with well-structured tool definitions, clear descriptions, and comprehensive parameter schemas. All 6 tools are explicitly registered with names, descriptions, and detailed input schemas. Descriptions are LLM-optimized (45-280 chars, averaging ~140), well above the 10-char minimum. All parameters have type definitions and descriptions. The server follows verb_noun naming convention (list, search, send, modify, respond). Key strengths: rich parameter constraints (enums, min/max ranges), dependency hints (account_name defaults to server's default), and multi-step tool composition patterns (accounts_list → emails_find → emails_modify). Weaknesses: no visible output schemas in source code (only input schemas shown), missing error handling guidance/recovery paths, and no documented constraints on operation categories (read vs write risks noted but not in descriptions). Tools use consistent naming and parameter conventions across the suite, enabling clean composition.

• Document output schemas for all 6 tools in emailTools.ts. Show the structure of emails_find results (fields: id, sender, subject, body_preview, date, is_read, is_flagged, attachments[]). Show accounts_list results (name, email, is_default). This is critical for downstream tool planning.
• Add error recovery guidance to write-operation descriptions. E.g., email_send: 'If recipient invalid, ensure address is RFC 5322 compliant. If quota exceeded, request user to clean up older drafts.' email_respond: 'If original email not found, try emails_find to locate it first.'
• Explicitly document mutually exclusive parameter sets. In emails_modify schema, add: 'Mark-state operations are mutually exclusive: use only one of (mark_read, mark_unread). Flag operations are mutually exclusive: use only one of (flag, unflag).'
• Implement idempotency and dry-run support. Add optional 'dry_run: boolean' parameter to email_send and email_respond (default false). Return what would happen without side effects. Add 'idempotent_key: string' parameter (UUID, replay-safe) to enable retry without duplicates.
• Clarify pagination contract. If limit=20 and 100 emails match, does emails_find return 20 with a next_cursor, or all 100? Add 'offset' and 'total_count' fields to response, or describe behavior in tool description.
• Verify response field naming matches parameter naming. If move_to_folder expects folder names like 'Trash', ensure folders_list returns folder names in the same format (not folder IDs or display names that require translation).