Single tool 'execute_skill_action' has a reasonable description (89 chars) and input schema with typed parameters, but critical gaps prevent higher scoring. The schema lacks output documentation entirely, LLMs cannot plan downstream calls without knowing what fields are returned. Parameter descriptions are present but minimal (e.g., 'Shipping address with city, state, and zip' lacks format/validation guidance). No error handling guidance, no recovery paths, and no indication of what the tool actually returns beyond the description. The tool name 'execute_skill_action' is generic and violates verb_noun clarity, 'calculate_sales_tax' would be more specific. No tool annotations (readOnlyHint, destructiveHint, idempotentHint) despite being READ_ONLY. The implementation in client.py shows hardcoded tax rates for only 3 states with no extensibility or error handling for unmapped jurisdictions.

• Add explicit output schema to tool definition: document that it returns {tax_calculation_id, destination_jurisdiction, cart_subtotal_usd, effective_tax_rate_pct, sales_tax_due_usd, nexus_determination, auto_filing_remittance_ready} with types and descriptions.
• Rename tool to 'calculate_sales_tax' (verb_noun) and update description to: 'Calculate sales tax due and nexus status for a given cart subtotal and shipping address. Returns effective tax rate, tax amount, and nexus determination (PHYSICAL_NEXUS_ESTABLISHED or ECONOMIC_NEXUS_ESTABLISHED).'
• Add enum constraint to 'state' parameter: {"type": "string", "enum": ["TX", "CA", "NY", ...], "description": "State abbreviation (2-letter code, e.g., TX, CA, NY)"}. If more states are supported, document the full list or add a discovery tool.
• Add format constraint to 'zip' parameter: {"type": "string", "pattern": "^\d{5}(-\d{4})?$", "description": "ZIP code (5 digits or 5+4 format, e.g., 78701 or 78701-1234)"}.
• Add error handling: document what happens for unmapped states (currently defaults to TX). Either expand the hardcoded jurisdiction map, add a 'supported_states' discovery tool, or return an error with available options.