search_by_isin

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

The description adds value beyond annotations: it details the return content (LEI, legal name, country, registration status) and failure modes, while annotations already confirm read-only and idempotent 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 three sentences, front-loading the main purpose, then usage guidance, return info, and failure conditions. Every sentence earns its place with no redundancy.

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 single-parameter tool, the description is complete: it explains the action, when to use, what is returned, and common failures. No output schema exists, but return details are given.

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 already fully describes the 'isin' parameter (pattern, length, example). The description reinforces the 12-character requirement and adds failure context, providing marginal additional semantics.

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 'Find', the resource 'issuer's LEI', and the specific input 'securities ISIN code (12 characters)'. It provides concrete usage examples and implicitly differentiates from sibling tools like 'search_by_bic' or 'lei_lookup'.

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 explicitly provides usage scenarios ('USE WHEN') and failure conditions ('FAILS WHEN'), guiding the agent on when to invoke this tool and what to expect in case of issues.

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