Guerrilla Mail MCP has clear, action-verb naming and visible input schemas for all 6 tools. However, descriptions are minimal (10-60 chars, well below the 194-char baseline), parameter descriptions lack detail, and output schemas are not documented. No error recovery guidance, no parameter constraints (enums, ranges), and no indication of which operations are idempotent or destructive in the descriptions themselves. The code shows proper schema registration and basic error handling via try-catch, but lacks LLM-optimized guidance for tool selection and recovery.

• Expand tool descriptions to 100 - 200 characters. Include WHAT the tool does, WHEN to use it, and what it returns. E.g., 'Get a new disposable email address from Guerrilla Mail and initialize a session. Returns the email address, alias, and session token. Call this first before checking inbox or setting a custom username.'
• Add descriptions to all parameters. For 'lang', specify valid codes (e.g., 'Language code (ISO 639-1, default en). E.g., en, es, fr, de.'). For 'seq', clarify format: 'Sequence ID to poll from (default 0). Pass the last email ID to fetch only newer messages.'
• Document output schemas in tool descriptions or as a separate schema field. E.g., 'Returns: {email_addr: string, alias: string, email_timestamp: ISO 8601 date, sid_token: string}'.
• Enhance error messages with recovery guidance. E.g., 'email_user is required. Provide a desired local part (before the @), e.g., "john123". Or call get_email_address() to use a random address.'
• Add a confirm_delete_emails tool or a dry_run parameter to delete_emails. Alternatively, document in the description that this operation is irreversible and should be called only after explicit user confirmation.