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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds valuable behavioral context: results are only 'candidates' and the user must verify fitment on the product page. This goes beyond the annotations by setting expectations about result certainty and the need for user confirmation.

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?

The description is two sentences with no fluff. The first sentence states the core purpose, and the second delivers an essential user instruction. Every word earns its place; it is highly efficient.

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?

While annotations and output schema exist, the high parameter count (10) creates gaps. The description establishes the primary use case and critical caveat, but it does not explain parameter combinations, the role of the q parameter, or shop/limit behaviors. It is adequate but not fully complete for a tool with this complexity.

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% (only pricing is described). The description adds meaning to registration and vehicle make/model/year parameters by framing them as input alternatives, but it leaves q, shop, limit, vehicle_cc, and lang unexplained. With 10 parameters, this is insufficient to compensate for the low schema coverage.

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 clearly states the tool finds product candidates for a registration plate or complete vehicle make/model/year. The verb 'find' is specific, the resource is product candidates, and it distinguishes from siblings by focusing on vehicle compatibility rather than generic product search or retrieval.

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 description implies when to use the tool (when you have a registration plate or vehicle details) but does not explicitly contrast with alternatives like search_products or get_product. It provides a key user-verification instruction but lacks clear 'when not to use' guidance.

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