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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: the lookup is free of charge and the data source is RDW, plus the breadth of returned attributes including a risk level. It does not mention rate limits or auth, but that bar is low given the annotations.

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?

A single sentence, front-loaded with the 'Free.' qualifier and the trigger condition before the long but load-bearing field list. Nothing is redundant, though the enumerated return fields make it slightly dense.

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?

For a single-parameter read-only tool with no output schema, the description compensates by listing what the response contains (APK expiry, insurance, recall, risk level) and naming the data source. An agent has enough to invoke and interpret it; only the sibling-routing detail for the paid reports is left implicit.

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?

One parameter at 100% schema description coverage, with the schema itself supplying the format example (GT-722-F). The description adds no syntax, format or normalization guidance beyond what the schema already provides, so 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 resource (Dutch licence plate / a specific car in the Netherlands) and enumerates exactly what it returns: make, model, age, fuel, Euro class, APK expiry, insurance, open recall, odometer verdict, risk level. The leading 'Free.' implicitly separates it from the paid siblings (nl_vehicle_report, buy_full_vehicle_report), though it never names them.

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?

Gives a clear trigger condition: 'Use when the user gives a Dutch licence plate or asks about a specific car in the Netherlands.' No explicit when-not or named alternative, but 'Free.' signals the paid-report siblings without spelling out the choice.

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