Single tool 'send_email' has a clear verb-noun name and proper JSON Schema with typed parameters (to, subject, body all strings, required array specified). However, the tool description is extremely brief (19 chars: 'Send transactional email'), falling below the 20-char minimum for meaningful LLM guidance. No parameter descriptions are visible in the schema, each param lacks a 'description' field explaining what it controls or accepts. The schema is minimal but present. No output schema is documented, leaving the LLM unaware of what fields to expect in the response (e.g., messageId, status, provider). No error handling guidance, recovery paths, or idempotency guarantees are specified. The tool lacks security annotations (no mention of credentials, permissions, or audit trails). Overall, this is a bare-minimum tool definition that would require significant enhancement for production use.

• Expand tool description to 50 - 150 characters explaining: what it does ('Sends a transactional email via configured provider'), when to use it ('Use when you need to notify a user or send a confirmation'), and what it returns ('Returns messageId and delivery status'). Reference pattern:tool-description.
• Add 'description' fields to all parameters: 'to' → 'Email recipient address (single email or comma-separated list)', 'subject' → 'Email subject line (plain text, max 255 chars)', 'body' → 'Email body content (HTML format; plain text will be auto-converted if needed)'.
• Document the output schema in the tool definition or in accompanying documentation. Specify: messageId (string), status (enum: 'sent'|'queued'|'failed'), provider (string), accepted (array of emails), rejected (array of emails with reasons).
• Add error handling guidance: 'If recipient email is invalid, returns error code INVALID_EMAIL with the offending address. If rate limit is hit, returns RATE_LIMIT_EXCEEDED, retry after 60 seconds. If provider is unavailable, returns PROVIDER_ERROR, check provider status or try a different provider.'
• Add security annotations: specify that credentials are injected server-side (not as parameters), declare this is a write operation (idempotent if messageId is provided), and note that all calls are logged for audit. Consider adding a dry_run parameter to preview without sending.

Inferred effective spec: <=2025-11-25.

• Relies on Sampling (deprecated) - integrate directly with the LLM provider API