validate_cusip

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

No annotations are provided, so the description carries full burden. It discloses that the tool checks the check digit and returns the expected digit on failure, but does not specify the return value for a valid CUSIP. This is a minor gap.

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?

Two concise sentences with no redundancy. The imperative 'USE THIS' front-loads the key action, making the purpose immediately clear.

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 validation tool with one parameter and no output schema, the description is adequate. It explains the verification logic and the outcome when the check digit fails. However, it lacks clarity on the success return value (e.g., true/false), which would improve completeness.

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 description adds context that the CUSIP is a North American securities identifier and includes an example. This adds marginal value beyond the schema's property description, sufficient for a baseline 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 tool's purpose: to verify a CUSIP by checking the mod-10 check digit. It specifies the resource (CUSIP) and the action (verify/check), distinguishing it from sibling validation tools.

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 instructs to use this tool when you have a 9-character string that might be a CUSIP and need verification. It implies a trust issue with naive 9-character acceptance. While it doesn't explicitly list alternatives, the context of sibling validation tools makes the use case clear.

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