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

With no annotations, the description carries the behavioral burden. It discloses the read-only nature ('Check', 'Returns'), the NHTSA vPIC source, the international scope, and notable output details such as do-not-drive and park-outside warnings and rewritten wording. It stops short of explaining what happens with missing or conflicting inputs.

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 front-loaded with the core action and contains no filler; every clause adds useful scope or output detail. It is slightly dense as a single long sentence, but the structure is acceptable given the tool's complexity.

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?

Given no output schema and no annotations, the description covers the main input alternatives, source scope, and return content well. The main gap is not explicitly stating that the caller must provide either a VIN or make/model/year (and optionally plate+country), nor how the tool behaves if no lookup key is supplied.

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 67%, so the description must compensate. It adds meaning by explaining VIN decoding via NHTSA vPIC, the conditional make/model/year grouping, and that the plate parameter is Netherlands/Israel-only and returns open recalls for that exact vehicle. It does not explicitly state which parameter combinations are required.

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 opens with a specific verb and resource: 'Check one vehicle for safety recalls.' It clearly distinguishes this from siblings like get_recall_notice, list_registers, and search_recalls by focusing on a single vehicle and combining multiple international registers.

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 gives clear context for when to use the tool: to check one vehicle by VIN or by make/model/year, with optional plate-based lookup. It does not explicitly name alternatives or state when not to use it, but the single-vehicle framing makes the intended use obvious.

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