nhtsa_decode_vin

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the VIN length constraint (17 characters) and lists the output fields, which is useful. However, it does not disclose potential failure modes (e.g., invalid VINs, partial decodes, or NHTSA API limitations) beyond the schema's min/max length.

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?

Three short sentences with no filler. The first sentence states the action, the second lists expected outputs, and the third provides the key input constraint. Every sentence earns its place.

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 full schema coverage and safety annotations, the description is nearly complete. It could mention that the NHTSA API may return partial data for invalid or incomplete VINs, but the minLength=11 in the schema already hints at partial VIN support. Overall, an agent has enough to call it correctly.

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%, so the schema already documents the vin parameter. The description reinforces that VINs are 17 characters, which matches the schema's maxLength, but adds no new semantic detail beyond what the schema provides. Baseline 3 is appropriate.

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 decodes a VIN and lists the specific output fields (make, model, year, engine, body class, drive type, plant info). It is distinct from sibling NHTSA tools like nhtsa_recalls or nhtsa_safety_ratings, which address different queries.

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 it (when you have a VIN and want vehicle specifications) but does not explicitly state when not to use it or name alternatives. Sibling tools like nhtsa_recalls or nhtsa_complaints are not mentioned, so an agent must infer the boundary from the tool name and description.

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