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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, so the safety profile is covered by structured data. The description still adds real behavioral value: it warns that some fields are not officially published and will self-report that, and it documents the error shape (list of valid countries) for an unknown country. It does not add rate limits or latency notes, so not 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?

Front-loaded with the primary use case, then the payload, then the alternative-tool rule, then the failure mode — a logical order with no filler. It is a dense single block, and the enumerated field list is long, which slightly dilutes scannability.

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?

Since an output schema exists, the detailed return-value enumeration is partly redundant, but the description still supplies what the schema cannot: the 'some fields are unpublished and say so' caveat, the sibling-tool routing rule, and the invalid-country error contract. Complete for an agent to call it correctly, with only minor redundancy.

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 coverage is 100%: the country parameter already documents accepted forms (name or id, e.g. 'UK', 'de', 'Germany') and points to list_tracks for valid values. The description adds only the reactive error behavior for an invalid country, so the baseline 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?

States a specific verb (returns) and resource (citizenship test info per country) and enumerates the exact payload fields (test name, format, question count, duration, pass mark, study levels, FAQ, sources). It also distinguishes itself from the sibling get_official_sources by noting it already embeds the official link.

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?

Opens by naming the exact user question this tool is the default for ('how does the citizenship test work in <country>?'), states the error condition (unknown country returns the valid list), and explicitly routes the agent to get_official_sources only when the link alone is sufficient. Both when-to-use and when-not-to-use are covered.

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