Decode a 17-character VIN to retrieve vehicle make, model, year, and specifications from NHTSA.
Decode a vehicle VIN to get make, model, year, and specifications from NHTSA.
| Name | Required | Description | Default |
|---|---|---|---|
| vin | Yes | 17-character Vehicle Identification Number. |
Changes observed during successful MCP inspections.
v0.1.11Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden but only names the data source. It does not disclose what happens with an invalid or non-17-character VIN, whether there is rate limiting, or whether authentication is required.
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?
A single front-loaded sentence with zero padding that names the action, input, and outputs in one pass.
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 one-parameter read tool with a fully described schema and no output schema, naming the returned fields is enough for an agent to call it correctly. Only minor gaps, such as invalid-VIN behavior, keep it from a 5.
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 100% and the single parameter is fully described in the schema as a 17-character VIN, so the baseline of 3 applies. The description adds no format or validation detail beyond what the schema already provides.
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 (decode), a specific resource (vehicle VIN), the returned fields (make, model, year, specifications), and the data source (NHTSA). An agent can distinguish this from siblings like nhtsa_recalls without opening either schema.
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 you supply a VIN, but gives no explicit when-to-use guidance, no prerequisites, and no mention of the sibling nhtsa_recalls tool that an agent might confuse for this one.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.