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

Annotations already communicate `readOnlyHint`, `openWorldHint`, `idempotentHint`, and non-destructiveness. The description adds useful contextual facts—source GLEIF, per-call pricing, and GET endpoint—but it does not disclose response format, pagination, or behavior when both `q` and `lei` are absent. With annotations covering the safety profile, the description provides moderate added value.

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 a single compact sentence that packs the tool's purpose, query modes, source, pricing, and endpoint without wasted words. It is front-loaded with the core purpose and every clause adds useful information.

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 two-parameter lookup with rich read-only annotations and no output schema, the description gives enough to invoke the tool correctly: the resource, the two search modes, the data source, the cost, and the HTTP method. The only minor omission is a note about providing at least one of `q` or `lei`, since neither parameter is required in the schema.

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 100%: both `q` and `lei` have examples and their meaning is documented. The description only restates the two query modes already present in the schema, so it adds little parameter-level meaning beyond what the input schema provides. The baseline of 3 is appropriate.

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 identifies the tool as an LEI lookup, states the resource (Legal Entity Identifier records), and specifies the two supported query modes: by LEI code or entity name. It is specific enough to distinguish from all sibling tools, none of which relate to LEI data.

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 makes the usage context clear: use this tool when you need an LEI record and have either an LEI code or an entity name. It does not explicitly name alternatives or exclusions, but among the sibling tools there is no close substitute, so the lack of explicit 'when not to use' guidance is not a significant gap.

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