13 tools with consistent naming (all get_* verbs) and basic descriptions (avg ~100 chars). However, critical gaps: NO input schemas visible in source code, all tools show only parameter names and descriptions, missing type definitions, enums, and constraints. Output schemas completely undocumented. No error handling guidance. Parameter descriptions lack format/range constraints (e.g., date format stated but no validation rules). No pagination support despite tools returning lists (get_recent_activities). Descriptions are generic and do not explain WHEN to use each tool vs. similar ones (e.g., get_heart_rate vs. get_stress both fetch daily metrics). Security: credentials injected via .env (correct), but no audit logging or permission gates visible.

• Add explicit JSON Schema to all 13 tools with type definitions (string, integer, object), min/max for numeric params (e.g., days: 1-365), and format constraints (date: YYYY-MM-DD). Use FastMCP's @mcp.tool decorator with proper input_schema parameter.
• Document output schemas in tool descriptions. Example: 'Returns: {recovery_status: string, recovery_percentage: number (0-100), recovery_metrics: {...}}'. Specify which fields are always present vs. optional.
• Add pagination to get_recent_activities and get_personal_records: include limit (default 20, max 100) and offset/cursor parameters. Return total_count and next_cursor in response.
• Enhance parameter descriptions with validation rules and error guidance. Example: 'date (ISO 8601, YYYY-MM-DD, max 365 days in past; defaults to today). If date is invalid, returns 400 with message: "Invalid date format. Use YYYY-MM-DD."'
• Add tool-selection guidance to descriptions. Clarify when to use get_heart_rate vs. get_stress vs. get_body_battery. Example: 'Use this for resting/average/max heart rate. For stress levels, use get_stress. For energy status, use get_body_battery.'

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

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry