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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so the safety profile is fully covered. The description still adds useful context beyond them: the authoritative source (GLEIF open data), that it is free with no auth, and that the payload is a compact due-diligence record. It does not say what happens when a name search returns multiple matches or returns nothing.

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 lead sentence plus two compact qualifiers. It is front-loaded with the verb and source, has zero filler, and every fragment (provenance, record shape, cost) earns its place.

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 read-only tool with no output schema, the description covers source, modes, and rough return shape ('compact due-diligence records'), which is close to sufficient. The one real gap is that no parameter is required yet the tool cannot function without one of q or lei — that constraint is left implicit.

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 coverage is 100%, with both q and lei fully documented, including examples and the 'when no LEI is known' condition. The description's 'exact' vs 'name search' phrasing essentially restates the schema rather than adding new meaning, so the baseline 3 applies.

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?

Names a specific verb and resource ('Global legal-entity lookup'), identifies the data source (GLEIF open data), and lists the two lookup modes (exact LEI vs name search). None of the siblings (validate_iin, fx_rates, search_listings) overlap, so an agent can route to it unambiguously.

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 gives clear mode-selection guidance: pass 'lei' for an exact match, or 'q' for a name search. What's missing is an explicit fallback rule (e.g. 'use q when the LEI is unknown, then disambiguate by jurisdiction'), and there is no statement of when to prefer this over validate_iin or another sibling.

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