uk_duty_calculator

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description adds a substantial amount beyond the annotations: rates are fetched live per request, unknown or non-declarable codes error with HMRC's message, origin-dependent measures surface as warnings, and there is a rate limit with 429 handling and a retry_after_seconds field. This is exactly the behavioral detail an agent needs and uses.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is longer than typical but every section serves a purpose: behavior, returns, limitations, related tools. The core purpose and formula are front-loaded, and optional details are clearly segmented. Some return-field details could be left to the output schema, but nothing feels wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity, the rich output schema, 6 parameters, external dependency (live GOV.UK Tariff), rate limits, and related workflows, the description is complete. It covers error behavior, retry logic, return fields, limitations, and alternative/related tools. An agent can predict the tool's behavior and side effects without further documentation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already covers all 6 parameters with detailed descriptions and examples, so the baseline is met. The description adds extra meaning by defining the CIF calculation, stating optional parameters default to 0, and noting that commodity_code may need extension from 6 to 8/10 digits. It doesn't fully expand on incoterm semantics, but the schema covers that.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource: 'Estimate UK import duty and VAT for a commodity code using the LIVE GOV.UK Trade Tariff'. It goes on to explain the calculation formula and clearly separates this tool from siblings like hs_code_lookup and incoterms_lookup, so an agent can tell which tool to invoke.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly identifies required versus optional inputs and provides related-tool guidance such as 'hs_code_lookup (find the 6-digit code first)' and 'incoterms_lookup (who actually pays these costs)'. It does not spell out exact 'use this instead of' conditions, but the context makes the intended usage clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.