validate_vin

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

With no annotations, the description fully bears the burden of transparency. It discloses that it checks the allowed alphabet (no I/O/Q) and the ISO 3779 check digit in position 9, and returns the expected check digit when validation fails. It does not state whether the operation is read-only or if there are side effects, but the disclosed internal logic is sufficient for understanding tool behavior.

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 extremely concise: two sentences, no fluff. The first sentence is front-loaded with an imperative action, and every clause provides valuable information. It perfectly balances brevity and informativeness.

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 one-parameter validation tool with no output schema, the description provides enough context: it explains what the tool does, what checks it performs, and what it returns on failure. It does not specify the return value on success, but that is typically implied (true or valid). Given the sibling context of many validation tools, the description sufficiently equips an agent to use 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 coverage is 100% (single parameter with description 'The 17-character VIN to validate'). The description adds context beyond the schema by clarifying that the VIN is for a vehicle and that the tool performs specific checks. This added meaning justifies a score above the baseline of 3.

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 verb 'verify' and resource 'vehicle VIN', and distinguishes it from other validation tools by specifying that it checks the allowed alphabet (no I/O/Q) and the ISO 3779 check digit. It explicitly instructs to 'USE THIS to verify a vehicle VIN before acting on it', leaving no ambiguity.

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 provides explicit when-to-use guidance ('before acting on it') and warns against assuming a 17-character string is valid. It does not explicitly name alternatives, but the sibling list of many validate_* tools implies that other identifiers should use the respective tool. A clear 'when not to use' or explicit alternative naming would improve it.

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