Single tool with basic structure but significant gaps in definition quality. The tool has a clear, verb-based name ('check_eligibility') and a concise description (87 chars), which is solid. Input schema is present with proper JSON Schema structure including types and descriptions for all parameters. However, output schema is not formally documented in the MCP server registration, it is only implicitly visible in the client.py code. The tool lacks error categorization guidance, does not document the structure of response fields, and missing descriptions for valid enum values (e.g., what does 'unopened' vs 'opened_unused' vs 'opened_used' vs 'damaged' mean to business logic). No tool annotations present (readOnlyHint, idempotentHint). The parameter descriptions are adequate but could be more precise about constraints and business rules. No evidence of error recovery guidance or input validation patterns.

• Add formal output schema documentation: {status: enum[approved|denied|manual_review], reason: string}. This enables agents to handle each outcome deterministically.
• Declare 'item_condition' as an enum with explicit values: ['unopened', 'opened_unused', 'opened_used', 'damaged']. This prevents hallucinated values.
• Declare 'product_category' as an enum. Either enumerate all values or mark as 'extensible enum' with known categories: [general, underwear, swimwear, perishables, cosmetics, electronics]. Add description of why certain categories have special rules.
• Improve error messages with actionable recovery: 'Invalid date format. Expected ISO 8601 (YYYY-MM-DD), e.g. 2026-06-15' and 'Item condition "opened_used" requires manual review. Contact support or escalate to customer_support_review tool.'
• Add tool annotations to the MCP tool definition: readOnlyHint=true, idempotentHint=true. This signals to agents that the tool is safe to call repeatedly.
• Enhance parameter descriptions with business rationale. E.g., 'product_category (string, required): The category of the item. Some categories (underwear, swimwear, perishables, cosmetics) are non-returnable unless unopened due to hygiene/safety regulations.'
• Add a 'format: date' or 'pattern: ^\d{4}-\d{2}-\d{2}$' constraint to date parameters in the JSON Schema, not just the description.