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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: public GLEIF provenance, no cost ('Free'), and the shape of the payload ('compact due-diligence records'). It does not disclose no-match behavior or rate limits, which keeps it below a 5.

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?

A single dense sentence, front-loaded with the verb and resource, then the two usage modes, then the value proposition. Every clause carries information; nothing is padding.

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 two-optional-parameter lookup with no output schema, the description covers the essentials: source, input modes, and rough result character. The notable gap is the zero-required-parameter case and what a name search returns (single best match vs candidate list), which an agent would need to know 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 100% and both parameters carry examples, so the schema already does the explanatory work. The description only restates the exact-vs-name-search split that the schema itself encodes ('legal name to search when no LEI is known'), adding no new syntax or matching 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?

States a specific verb and resource ('legal-entity lookup') plus the authoritative source (GLEIF open data), which is far more than a restatement of the title. It does not explicitly contrast with siblings, but none of the listed siblings (validate_iin, verify_agent, search_listings) overlaps in resource, so confusion risk is low.

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 gives the routing rule between the two modes: pass 'lei' for an exact match, or 'q' for a name search. It leaves open what to do when neither is supplied (both parameters are optional) or which takes precedence if both are given, so it stops short of full when/when-not guidance.

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