The server has 5 tools with complete input schemas visible in src/server.ts. All tools are properly named with action verbs (send_, get_, create_) and descriptions are present. However, several issues limit the score: (1) Descriptions are mostly generic and lack WHEN/WHY guidance; (2) Parameters lack type information in descriptions (e.g., 'phone number in E.164 format' is stated in description but not validated); (3) Output schemas are NOT documented, tool responses are JSON stringified but no structured schema is declared for the LLM; (4) Error handling is minimal, no recovery guidance visible in error paths; (5) No enum constraints on parameters that should be restricted (e.g., message limits, status values). Tool names follow verb_noun convention well. Parameters are reasonable but lack consistency in documentation depth.

• ADD OUTPUT SCHEMAS TO ALL TOOLS. For each tool, document what fields are returned. E.g., send_sms: {message_sid, status, created_at, to, from}. Document in tool definition or in post-call handler comments.
• ENRICH DESCRIPTIONS WITH CONTEXT. Rewrite each description to include WHEN/WHY. E.g., 'send_sms: Send an SMS message via Twilio. Use this when you have a recipient phone number and message text. Creates or links to a conversation for tracking. Returns message_sid for status tracking.'
• ADD SCHEMA CONSTRAINTS. Encode min/max, minItems, patterns directly in JSON Schema. E.g., limit: {type: 'number', minimum: 1, maximum: 1000}, participants: {type: 'array', minItems: 2}.
• IMPLEMENT ERROR RECOVERY PATTERNS. Wrap tool calls in try-catch with actionable error messages. E.g., 'messageSid not found. Did you mean: [list of recent SIDs]?' or 'Invalid phone number. Use E.164 format: +1234567890'.
• ADD PAGINATION CURSOR/OFFSET. For get_inbound_messages, add optional 'offset' or 'cursor' parameter. Return 'has_more' and 'next_cursor' in response. Document in tool description.
• DOCUMENT PARAMETER RELATIONSHIPS. In send_sms, explicitly state: 'Either conversationId (to link to existing thread) or omit (creates new thread). Do not use both simultaneously.'
• VALIDATE INPUTS SERVER-SIDE. Check E.164 phone format, message length (1-1600), limit range (1-1000). Return specific errors: 'Invalid to: "+123" is not E.164 format. Use +[country][number], e.g., +12025551234'.
• ADD IDEMPOTENCY HINTS. If send_sms should be idempotent (same phone+message = same result), document this and add an optional 'idempotency_key' parameter. Mark tool with idempotentHint annotation.