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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds meaningful context beyond annotations by disclosing that results carry a data version and as-of date, which helps an agent reason about data freshness; it does not cover source, update frequency, or return volume, preventing a 5.

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 a single, front-loaded sentence that states the resource, included rate types, and freshness metadata. Every clause earns its place, with no redundant or vague phrasing.

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?

For a simple three-parameter read-only lookup with full schema documentation and no output schema, the description gives enough information about what the data contains (standard/reduced rates, version, as-of date). It remains slightly incomplete because it does not clarify the return shape or how it differs from the similarly named VAT/GST sibling.

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?

Schema description coverage is 100%, so region, country, and currency are fully documented in the schema. The description restates the country-oriented nature of the data but adds no syntax, format, or filtering nuance beyond what the schema already provides, matching the baseline of 3 for high schema coverage.

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 clearly states the resource and content: VAT and GST rates by country, including standard and reduced rates plus version/as-of metadata. It distinguishes the tool from most siblings but does not differentiate it from the closely named converters_vat_gst sibling, leaving ambiguity about which one retrieves rates versus calculates them.

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?

Usage is implied by the reference-data nature of the tool, but the description gives no explicit when-to-use guidance, prerequisites, or comparison to alternatives such as converters_vat_gst or converters_exchange_rates. An agent can infer it is for looking up rates, but not confidently choose it over the sibling without inspecting schemas.

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