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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context — results are 'candidates', not confirmed fits, and the user must verify on the product page. However, it omits the pricing='customer' session requirement and whether registration and make/model/year are mutually exclusive.

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?

Two sentences, front-loaded with the action and immediately followed by the verification caveat; no filler. It is arguably too terse for a 10-parameter tool, but nothing present is wasted.

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?

An output schema exists, so return values need no explanation. Still, with 10 optional parameters at 10% schema coverage, the description leaves unresolved which parameters belong to which input mode, whether registration excludes make/model/year, and how shop/lang/limit defaults apply.

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 only 10% across 10 parameters; only 'pricing' is documented in the schema. The description names the two input styles, partially mapping to registration and vehicle_make/model/year, but says nothing about q, lang, shop, limit, or vehicle_cc, so most parameters carry no semantic explanation anywhere.

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 and resource ('Find product candidates') and names the two input modes (registration plate vs. make/model/year), which is more specific than a generic search. It does not, however, differentiate itself from the sibling search_products/get_product tools, so an agent must infer the boundary.

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?

The input modes imply the scenario ('registration plate or a complete vehicle make/model/year'), but there is no explicit when-to-use, when-not-to-use, or routing to search_products/get_product. The only imperative ('Always ask the user to verify fitment') is a caution, not usage guidance.

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