Single tool 'execute_skill_action' has critical definition gaps. Description is present (97 chars) but vague, does not explain WHAT operations it performs, WHEN to use it, or what it returns. Input schema exists but is severely underspecified: single string parameter 'query_payload' with no format, constraints, or examples. No output schema documented. Tool name uses generic verb 'execute' rather than domain-specific action (e.g., 'estimate_tariff', 'calculate_duty'). No error handling guidance. No parameter validation rules. Fails to match domain intent (cross-border duty estimation) in interface design.

• Rename tool to 'estimate_tariff_duty' or 'calculate_customs_tax' to signal domain action and match verb_noun convention.
• Replace 'query_payload' string parameter with structured input schema: {hs_tariff_code (string, pattern: \d{10}), declared_value_usd (number, min: 0.01), origin_country (enum: [US, DE, GB, ...]), destination_country (enum: [US, DE, GB, ...])}. Add description to each field.
• Document output schema explicitly: {tariff_calculation_id (string), hs_tariff_code (string), import_duty_usd (number), import_vat_usd (number), total_customs_tax_usd (number), ddp_delivery_duty_paid_certified (boolean), customs_breakdown_url (string)}.
• Expand description to 100-150 chars: 'Estimate cross-border customs duty and VAT for a shipment. Provide HS tariff code, declared value (USD), origin and destination countries. Returns itemized duty, VAT, and total tax due.'
• Add error handling: return structured error with invalid_field, constraint_violated, and recovery_hint (e.g., 'Invalid HS code. Must be 10 digits. See https://harmonized-tariff.example.com').