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

Annotations already mark the tool as read-only, idempotent, open-world, and non-destructive, so the bar is lower; the description still adds substantial behavior beyond that: cascading through multiple lookup endpoints, graceful degradation if GLEIF or OpenFIGI is unavailable, returning figi_candidates on ambiguity rather than asserting, and explicitly reporting unresolved identifiers. No annotation contradiction exists.

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 appropriately front-loaded with purpose and 'Use FIRST,' but the SUPPORTED TYPES section is dense, uses long nested parentheticals, and repeats the name-to-ID idea. The content is valuable, but readability would improve by separating the two entity types and trimming redundant rationale.

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?

With no output schema, the description carries the burden of explaining return behavior, and it does so well: CIK, ticker, company_name, LEI with ownership, FIGI, RxCUI/ingredient/brand/citation, figi_candidates for ambiguity, and unresolved identifiers. Graceful degradation and source labelling are also covered, leaving no major gap for selection or invocation.

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%, but the description adds critical meaning beyond the schema: it documents ISIN as an accepted company input, instructs callers to pass the bare entity name rather than the full noun phrase, and explains why trailing security-class words cause FIGI lookup failure. This is exactly the kind of semantic guidance a schema alone rarely provides.

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 states a clear verb and resource: resolve user-spoken names to canonical/official identifiers other tools require. It opens with concrete query examples and explicitly says 'Use FIRST whenever you have a name but need an ID,' which distinguishes it from sibling lookup/profile tools. It also enumerates supported types, making its scope immediately recognizable.

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 explicit when-to-use guidance: 'Use FIRST whenever you have a name but need an ID,' and explains when 'company' vs 'drug' applies, including acceptable input forms. It does not name specific sibling tools to avoid in favor of this one, so exclusions are implied rather than stated.

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