Single tool 'send_email' has a clear action verb and reasonable description (73 chars). Input schema is present with Zod validation (subject: string min 1-200, body: string min 1). However, parameter descriptions are minimal, 'Email subject line' and 'Email body content' lack context about format, length rationale, or when to use the tool. No output schema is documented; the response is inferred from code (text content with email ID). Error handling exists but is generic ('Server not configured'). The tool is write-heavy (WRITE risk) but lacks idempotency guidance or confirmation pattern. No tool annotations (destructiveHint, idempotentHint) present. Overall: functional but below production baseline for parameter documentation and output clarity.

• Expand parameter descriptions: 'subject (1-200 chars): Email subject line. Keep concise for readability in inboxes.' and 'body (1+ chars): Email body in plaintext. HTML and markdown are not supported; use \n for line breaks.'
• Document output schema explicitly: 'Returns {content: [{type: "text", text: string}]} with email provider ID. Use provider ID for tracking/debugging.'
• Add tool annotations to the send_email registration: destructiveHint=true, idempotentHint=false. This signals to agents that repeated calls have side effects.
• Implement a dry-run parameter (optional, default false) or a separate preview_email tool so agents can validate before sending.
• Improve error messages: 'Server not configured: set RECIPIENT_EMAIL env var (comma-separated emails). Example: [email protected],[email protected]' and 'Email provider error: {provider_message}. Retryable: {true|false}. If retryable, wait 5s and try again.'