Single tool with minimal definition quality. Tool name follows verb_noun convention correctly ('write_email_draft'), but description is extremely sparse at 56 characters. Input schema is fully present with proper types and field descriptions, but output schema is completely undocumented. No error handling guidance, no security considerations for credential management, and no documentation of side effects. The tool modifies state (creates Gmail draft) but this critical fact is buried in the description rather than explicitly stated. Tool exhibits high-risk WRITE operations without confirmation or dry-run capability.

• Expand tool description to 100-200 characters. Template: 'Create a Gmail draft without sending. Requires valid recipient email, subject, and body text. Returns draft ID for later editing or sending. Does not send the email, drafts remain in Drafts folder until manually sent.'
• Document output schema explicitly. Add to docstring or code comments: 'Returns dict with keys: id (str, draft ID), message (dict, message metadata), error (str, error message if failed). Example: {"id": "abc123", "message": {...}}'
• Add email format validation to recipient_email parameter. Update description: 'Email address of the recipient (must be valid RFC 5322 format, e.g. user@example.com)'. Add regex pattern constraint or validation inside function.
• Document credential handling in tool description: 'Credentials are injected server-side from GOOGLE_TOKEN_PATH and GOOGLE_CREDENTIALS_PATH environment variables. User email is read from USER_EMAIL environment variable. No credentials are passed as parameters.'
• Add error recovery guidance to description: 'Returns error field with message if draft creation fails. Common causes: invalid recipient email, missing credentials, rate limiting. If rate limited, retry after 30 seconds.'
• Declare required permissions explicitly. Add docstring line: 'Required scope: https://www.googleapis.com/auth/gmail.compose (can create drafts only, cannot send).'
• Consider adding optional dry_run parameter (boolean, default false) to support confirmation pattern. When true, validate inputs without creating draft, returning validation results. Enables agent to verify input before actual creation.