validate.isin

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

No annotations exist, so the description carries full burden. It discloses validation logic (Luhn check), format, return fields (valid, country, nsin, CUSIP), and a special feature (catching transposed chars). It does not discuss error handling or rate limits, but covers core behavior well.

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 sentences effectively communicate purpose, structure, returns, and a key behavior. The first sentence front-loads the primary action and format, while the second adds valuable output details. No wasted words.

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 without an output schema, the description covers format, validation, return values, and a special edge-case behavior. Missing details on error responses or response schema, but overall sufficiently complete for its complexity.

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 schema describes the parameter as '12-character ISIN.' The description adds significant meaning by breaking down the ISIN structure (country, NSIN, check digit) and noting CUSIP extraction for US/CA. This enriches the schema's minimal description.

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 it validates an ISIN, explains its structure (2-letter country + 9-char NSIN + Luhn check digit), and distinguishes from sibling tools by specifying what it returns (country, nsin, CUSIP for US/CA).

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?

No explicit when-to-use or when-not-to-use guidance is provided. While the distinct name and purpose imply usage for ISIN validation among siblings with different identifiers, there is no direct comparison or exclusion criteria.

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