9 tools with basic schemas and descriptions, but significant gaps in parameter documentation and error handling. All tools have names starting with action verbs (send_, list_, get_, check_, mark_, download_, set_) which is good. Descriptions are present but brief (avg ~60 chars, below the 194-char baseline). Input schemas visible for all tools with type declarations, but parameter descriptions are minimal and lack constraints (enums, ranges, format specs). No output schemas documented. Error handling is absent, no recovery guidance, no categorization of retryable vs fatal errors. No tool annotations (readOnlyHint/destructiveHint). Security concern: file paths accepted as parameters without clear validation guidance.

• Document output schemas for all tools. Example: list_chats should return {chats: [{jid: string, displayName: string, unreadCount: number, isGroup: boolean}], total: number}. This enables agents to chain tools and extract required IDs.
• Add parameter constraints to descriptions. For 'to' parameter: 'WhatsApp JID (format: [email protected] or [email protected]), contact name (case-insensitive), or phone number (digits only, 10-15 chars).' Use enums where applicable (e.g., limit parameter: 1-100, default 50).
• Expand tool descriptions to 100-200 chars. Include: what it does, when to use it, prerequisites (e.g., 'Requires active WhatsApp connection; call check_connection first if unsure'), and side effects (e.g., 'Marks messages as read in the recipient's view').
• Add tool annotations: mark send_message, send_file, set_contact_name, mark_read, download_media with destructiveHint=true. Mark list_chats, get_chat_history, get_contact_info, check_connection with readOnlyHint=true. This guides agent planning.
• Add error handling guidance to tool descriptions. Example for send_file: 'Returns error if file not found, unreadable, or outside inbox directory. If path traversal detected, returns 'refusing to send channel state' error. Retry with a valid local file path.'