Gmail MCP has clear, verb-prefixed tool names (list_emails, get_email, search_emails, list_labels) and reasonable descriptions (avg 65 chars). All tools have input schemas with type constraints (minLength, min/max for numbers). However, parameter descriptions are minimal (avg 45 chars), output schemas are undocumented, and error handling is absent. No guidance on what fields are returned or how to chain tools. Lacks pagination documentation despite maxResults cap at 50. No error recovery patterns.

• Document output schemas for all tools. Specify fields returned by list_emails (e.g., messages: [{id, from, subject, snippet, date}], total_count), get_email (full message structure), search_emails (same as list_emails), and list_labels (labels: [{id, name, type}]).
• Expand parameter descriptions to 60 - 100 chars. For 'query' param, add: 'Gmail search syntax (e.g., from:[email protected], subject:urgent, has:attachment). See https://support.google.com/mail/answer/7190 for full syntax.'
• Add error recovery guidance. E.g., 'If messageId is invalid, try search_emails() first to find the correct message ID. If search returns no results, verify the query syntax.'
• Document pagination behavior. Add to list_emails and search_emails: 'Results are limited to maxResults (default 10, max 50). To fetch more, use offset or cursor-based pagination (if supported by Gmail API).'
• Clarify tool selection. Update list_emails description: 'Lists messages in INBOX only, optionally filtered by query. Use search_emails for broader searches across all folders.' Update search_emails: 'Searches all Gmail messages (not just INBOX) using Gmail query syntax.'