Strong foundation with 15 well-named tools, consistent descriptions (avg ~120 chars), and visible input schemas. All tools follow verb_noun naming convention. Descriptions are action-oriented and explain WHAT/WHEN. However, output schemas are not documented in the source code provided, parameter descriptions lack format constraints (e.g., no regex patterns, min/max for numeric fields), and error handling guidance is absent. No tool annotations (readOnlyHint, destructiveHint, idempotentHint) despite clear risk classifications. Composition is sound, tools are single-responsibility and chainable (e.g., search_emails → get_email_content → reply_email). Prompts and resources are well-designed but not evaluated in this dimension.

• Document output schemas for all tools. E.g., search_emails should return {emails: [{uid: number, from: string, subject: string, date: string, unread: boolean}], total: number}. This enables LLMs to chain tools correctly.
• Add format constraints to parameter descriptions. E.g., 'limit: Maximum number of results (1 - 100, default: 20)', 'uid: Email unique identifier (positive integer)', 'query: Search text (1 - 500 characters)'.
• Add tool annotations to schema. Mark destructive tools with destructiveHint=true, non-idempotent tools with idempotentHint=false, and read-only tools with readOnlyHint=true. This is a 2026-07-28 spec requirement.
• Add error handling guidance to tool descriptions. E.g., send_email: 'Returns error if recipient is invalid (try search_users to verify email) or SMTP connection fails (retryable).'
• Implement confirmation pattern for delete_folder and delete_emails(permanent=true). Return {status: 'pending_confirmation', message: 'Delete folder X? This cannot be undone.', confirmationToken: '...'} and require a confirm_delete tool call with the token.