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

Annotations already cover the safety profile (readOnly, openWorld, idempotent), so the description's job is billing and scope — and it delivers: 0.08 USDC via x402 or 40 credits of a Factline API key, plus the input delimiter. It omits latency or rate-limit behavior, so a 5 is not earned.

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 dense but well front-loaded sentence: purpose first, then output inventory, then input format, then cost. It is long but nearly every clause carries a distinct fact (metrics list, best-per-metric, cost) that an agent needs before invoking.

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 wisely enumerates what comes back (liveability, crime, home values, distances, noise, air quality, ground height, best address per metric, full property report per address). Combined with pricing and input format, this is close to complete; only pagination/response-size and error behavior are absent.

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% and the single parameter already documents the ';' separator and the 2–5 range with an example. The description restates the same delimiter rule, adding no new syntax or format meaning beyond the schema, 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 (compare) plus resource (Dutch addresses) and an explicit scope of 2 to 5 inputs, in English. It is clearly distinguishable from nl_home_basic (single address basics) and nl_home_report (single full report) because it aggregates both plus the best-per-metric verdict.

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?

Names concrete use cases (house-hunting, relocation, real estate agents), which is clearer context than most siblings give. It does not, however, explicitly say when to prefer it over nl_home_report or nl_home_basic, nor when-not to use it (e.g. single-address cases).

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