UCP Client exposes 18 e-commerce tools with consistent naming (verb_noun pattern) and complete JSON schemas. All tools have descriptions and input parameters are typed. However, descriptions are brief (avg ~80 chars, below the 194-char baseline), lack actionable context for LLM selection, and omit critical details like prerequisites, return structures, and error recovery guidance. Parameter descriptions exist but are minimal. No output schemas documented. Error handling is absent, tools do not guide recovery or categorize failures. Security considerations (secrets, permissions, audit) are not visible in tool definitions.

• Expand tool descriptions to 100-200 chars. Include WHAT the tool does, WHEN to use it (vs similar tools), and WHAT it returns. E.g., 'Set the fulfillment method (shipping or pickup) for a checkout. Call this after creating a checkout and before selecting a destination. Returns the updated checkout with available fulfillment options.'
• Document output schemas for all tools. Specify the structure of returned objects, required fields, and IDs needed for chaining. E.g., create_checkout should document that it returns {id, status, line_items, totals}.
• Add error recovery guidance to descriptions. E.g., complete_checkout: 'If payment fails, the checkout remains open, retry with a different payment method or call cancel_checkout to abort.'
• Enhance parameter descriptions with format/constraint hints. E.g., 'Discount code (alphanumeric, 3-20 chars, case-insensitive)' instead of just 'Discount code to apply'.
• Implement confirmation/dry-run for irreversible operations. Add a 'dry_run' boolean parameter to complete_checkout so agents can preview totals and payment validation before committing.