nhtsa_decode_vin

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

The annotations already declare readOnlyHint=true, so safety profile is known. The description adds return field details but does not mention potential errors, invalid VIN handling, or output format. This is adequate given the read-only annotation, but not rich.

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 concise, front-loaded sentences cover purpose, outputs, and input constraint with no wasted words. Each sentence adds distinct value.

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 simple single-parameter tool with no output schema, the description lists the primary return fields and input length. It lacks detail on response structure or failure modes, but those are not critical for a straightforward decoder.

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?

The input schema fully documents the 'vin' parameter with type, length constraints, and description. The description's 'VINs are 17 characters' is redundant with the schema. No additional parameter semantics are provided beyond the schema.

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's function with a specific verb ('Decode') and resource ('Vehicle Identification Number'), and lists expected output fields (make, model, year, engine, etc.). This distinguishes it from sibling NHTSA tools like recalls or complaints.

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 clear usage context: when you have a VIN and want vehicle specifications. However, it does not explicitly mention alternatives or when not to use this tool, though the 'decode' purpose makes the use case evident.

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