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

With no annotations, the description carries the full burden and does disclose key behavior: output always contains parents.direct and parents.ultimate (null if unreported), plus BIC/mapped ids, addresses and status, and it states the price ($0.005 USDC). It does not say what happens when no lookup key is supplied (0 required params) or how multiple params interact.

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 output guarantees are front-loaded in the first two sentences and the pricing/alternative routing follows. It is dense and somewhat sales-flavored ('Upsell', repeated '$0.05/$2.50'), but every sentence carries decision-relevant information for the agent.

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 4-parameter, no-annotation, no-output-schema tool, the description covers return contents, cost and sibling routing well. It stops short on parameter interplay, the zero-key case, and error behavior, which an agent needs before calling.

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 description coverage is 0%, so the description must define all four parameters. It names lei, name and registered_as but gives no semantics for any of them (no format hints, no explanation of what registered_as means, no note on whether name requires country), and it omits country entirely.

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 and resource ('GLEIF LEI lookup') and names the key lookup fields (lei/name/registered_as), which distinguishes it from lei_full, the batch/name-matching variant. The purpose is clear, though the terse slash-delimited field list is less readable than a plain sentence would be.

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?

It explicitly routes the agent elsewhere for a common alternative case: 'Upsell lei_full for up to 10 name matches' and 'Screen many name matches with parents: /lei-full'. That is clear conditional guidance, but there is no guidance on when to prefer lei vs name vs registered_as, or on combining parameters.

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