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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered; the description adds value beyond them by disclosing the data sources (BAG, CBS, Leefbaarometer), the language of results (English), and the cost profile ('Free'). It does not describe failure behavior for unknown addresses, which keeps it at 4.

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?

Three sentences, front-loaded with 'Free.' and then the trigger, then inputs, then sources. Every clause carries distinct information and nothing is repeated from the schema or annotations.

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 no output schema, the description must convey what comes back, and it does so by listing the fact categories and result language. Sources are cited for provenance. Minor gaps remain on pagination/not-found behavior, but for a read-only lookup it is close to complete.

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% with per-field descriptions, so the baseline is 3. The description adds the non-obvious either/or semantics ('Accepts postcode + house number or free text'), clarifying that q and the postcode fields are alternative input modes rather than a combined requirement.

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 the resource (Dutch address/home facts) and enumerates the concrete data points returned: year built, floor area, use, neighbourhood residents, average home value, liveability percentile. 'Free' and the 'basic' name implicitly separate it from paid siblings like buy_full_address_report and nl_home_report, but no sibling is named 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?

It gives a clear trigger ('Use when the user mentions a Dutch address or asks about a home in the Netherlands') and notes the free tier, which is the main selection axis against paid siblings. There are no explicit exclusions or named alternatives, so it stops short of a 5.

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