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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and openWorld=false, so the safety profile is covered. The description adds one useful behavioral fact beyond the annotations - that each value carries its official source - but says nothing about caching, freshness across tax years, or whether missing country/year combos error out.

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 front-loaded sentence that lists the returned data classes immediately, with no filler. It is a fragment rather than a complete sentence, but every phrase earns its place.

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?

With an output schema present, return-value structure need not be explained, and the read-only annotations cover the safety profile. The description adequately conveys what data comes back for which country/year, though it omits any hint about failure cases or parameter defaults.

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%, including the UK start-year convention and the DE/UK/GB enum note, so the schema does the heavy lifting. The description only restates 'for the country and year' without adding format or constraint detail beyond the schema.

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 resource set - allowances, tax bands, contribution rates and ceilings for a country and year - which is clearly distinguishable from the calculate_* siblings that perform computations. It stops short of a verb ('retrieve'/'fetch') and leans on the title, but the resource is unambiguous.

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?

There is no statement of when to use this tool versus calculate_gross_salary, calculate_net_salary, or list_salary_countries, and no prerequisites or exclusions. The intended use (fetching raw reference data rather than computing a salary) can only be inferred.

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