vatcomply_rates

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds the useful detail that results are broken out into standard/reduced/super-reduced tiers, but says nothing about rate freshness, effective dates, or whether non-EU country codes return empty results.

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?

A single well-formed sentence with the resource and the returned tier breakdown front-loaded; nothing is wasted. It is however terse to the point of leaving useful context out.

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 one-optional-parameter read with no output schema, the description gives enough to understand the domain but not the response shape (e.g., whether results are keyed by country code) or whether historical rates are available. Adequate but with clear gaps.

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?

With a single parameter and 100% schema description coverage, the schema already fully documents country_code including the 'omit for all EU countries' behavior. The description adds no semantics beyond the schema, so the baseline of 3 applies.

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 names a specific verb and resource ('Get EU VAT rates') and specifies what dimensions are returned (standard, reduced, super-reduced, per country). It does not acknowledge the sibling vatcomply_countries, which is the obvious alternative for the country list itself, so an agent has to infer the boundary between the two.

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 context is only implied: the schema note 'omit for all EU countries' hints at the all-countries case, but the description says nothing about when to pick this over vatcomply_countries or any other lookup. No exclusions or prerequisites are stated.

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