The server defines 12 tools with mostly complete schemas and descriptions, but has significant gaps in error handling, parameter constraints, and output documentation. Naming follows verb_noun conventions well (search_contacts, list_messages, send_message). Descriptions are present for all tools (range 50-180 chars, within baseline 194 avg) and all parameters have descriptions. However, schemas lack comprehensive constraints (no enums, no min/max for numeric params), error handling provides no recovery guidance, and output schemas are not explicitly documented. The WRITE operations (send_message, send_file, send_audio_message) lack confirmation/dry-run patterns despite irreversible side effects. No mention of pagination limits being enforced, list_messages and list_chats accept pagination but output structure is not documented. Security concern: no evidence of credential injection, no scope declarations, no audit logging visible in the provided code. The Go backend (whatsapp-bridge) is not directly exposed but relied upon; the Python MCP server acts as a gateway. Per-tool assessment: naming is consistently strong (verb-first); descriptions adequate but generic in places; schemas present but underspecified (missing constraints, output types).

• Document output schemas for all tools. Specify return type (object, array), required fields, field types, and sample structure. E.g., search_contacts should return {contacts: [{name: string, phone: string, jid: string}, ...], total: integer}.
• Add dry-run parameters to send_message, send_file, send_audio_message. E.g., dry_run: boolean (default false). When true, return validation result without sending. This prevents accidental message spam.
• Document pagination limits explicitly. Specify that limit defaults to 20, max is 50, and list_messages/list_chats/get_contact_chats enforce this cap server-side.
• Add error recovery guidance to parameter descriptions. E.g., for recipient param in send_message: 'Valid formats: phone number with country code (e.g. 14155552671) or JID (e.g. 14155552671@s.whatsapp.net or 123456789@g.us). If phone fails, try JID format.'
• Introduce enum constraints or validation rules. E.g., sort_by in list_chats should be restricted to ["last_active", "name"]. Document in description: 'Must be one of: last_active (default), name'.
• Add tool annotations to fastmcp tool definitions. Use readOnlyHint for READ tools (search_contacts, list_*, get_*) and destructiveHint for WRITE tools (send_message, send_file, send_audio_message).
• Document scope requirements. Each tool description should state required permissions: 'Requires: read:messages' or 'Requires: write:messages'. This guides least-privilege agent configuration.
• Add idempotency guidance. For tools that might be retried (list_messages with same params, get_chat, etc.), clarify that repeated calls return consistent results.