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

Annotations already declare readOnly=true, openWorld=false, destructive=false, so the safety profile is covered. The description adds genuinely non-obvious behavior: the data is reused from public-sector sources, carries a CC BY 4.0 licence, and must be attributed using the result's own attribution or attribution.source.statement. No return-shape detail, but an output schema exists.

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?

Front-loaded with the one-line purpose, then the sibling relationship, then the licensing note. The attribution sentence is dense but does real work; overall there is no filler, though the licence text could be tightened.

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 documenting the return shape, zero parameters, and annotations covering safety, the description supplies everything else an agent needs: what it lists, how it pairs with search_tax_treaties, and the mandatory attribution requirement.

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 tool takes zero parameters, so there is no parameter semantics for the description to add. Baseline for 0 params 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?

States a specific verb and resource with scope: 'List all countries with an Irish double-taxation treaty.' It also distinguishes itself from the sibling search_tax_treaties, which is named explicitly as the filtering counterpart.

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?

'Use with `search_tax_treaties` to filter results by country' tells the agent how this tool pairs with the sibling, implying this one enumerates and the other narrows. It stops short of an explicit when-to-use/when-not-to-use statement, but the routing intent is clear.

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