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

Annotations already establish readOnly, idempotent, non-destructive and closed-world behavior, so the bar is lower. The description adds real value beyond them by enumerating the substance returned: who pays, what is taxed (assets, thresholds, prior residence period), deferral/relief, the legal norm with link, and the date checked — which signals source freshness the annotations do not cover.

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?

One front-loaded sentence answers the core question first, then enumerates the supporting payload in a parenthetical list. No filler, no restatement of the title, and the density is appropriate for a lookup tool.

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 only two optional parameters and no output schema, the description needs to convey the return payload, and it does so thoroughly (determination, thresholds, relief, legal basis, check date). A minor gap remains around multi-country requests and response shape, but the definition is otherwise sufficient to call correctly.

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%, with both parameters (version, countries) fully documented including defaults and enum lists, so the schema carries the burden. The description only hints at country scoping through 'whether a country levies' and adds nothing about the version/language parameter or behavior when multiple countries are supplied.

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 states precisely what is retrieved: whether a country levies an exit/departure tax on individuals relinquishing tax residence, plus the supporting detail set. The resource ('exit tax on individuals') is specific enough to separate it from siblings like check_residency or tax_burden, though it never names an alternative explicitly.

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 only implied by the subject matter: it applies to individuals giving up tax residence and covers deferral/relief such as intra-EU/EEA moves. There is no statement of when to choose this over check_residency or tax_burden, and no exclusions or prerequisites (e.g. whether it applies to companies).

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