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

Even with strong annotations (readOnly, openWorld, idempotent, non-destructive), the description adds substantial behavioral context: internal cascading through multiple lookup endpoints, graceful degradation when GLEIF/OpenFIGI are unavailable, explicit `unresolved` output rather than omission, source-labelling of identifiers, and ambiguity handling via `figi_candidates`. This is far beyond what the annotations already provide.

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 front-loaded with examples and a clear directive, but the bulk consists of extremely long, heavily parenthesized run-on sentences that are hard to parse. Every clause carries useful information, but the structure is not concise; a bulleted or sectioned layout would serve an agent much better.

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 compensates thoroughly: it enumerates the returned identifiers for each type (CIK, ticker, LEI, FIGI, RxCUI, ingredient, brand, citation), covers ambiguous and unresolved cases, and discloses failure modes like unavailable enrichment sources. Nothing essential to invoking the tool correctly is missing.

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%, so the baseline is 3, but the description adds real semantic value: it notes ISIN as an accepted company input, explains that non-equity instruments without tickers still resolve via name search, and clarifies how ambiguous names are reported. This goes beyond the schema without being redundant.

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 opens with concrete user-phrase examples and immediately states the core purpose: resolving a user-spoken name to canonical/official identifiers other tools require as input. It enumerates supported entity types and the specific identifier sources, which clearly differentiates it from sibling tools like entity_profile or compare_entities that do analysis rather than identifier lookup.

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 says 'Use FIRST whenever you have a name but need an ID,' which is a clear when-to-use directive. It also explains supported inputs per type and describes how to interpret ambiguous results. However, it does not name alternative tools or state explicit when-not-to-use conditions, so it stops short of a 5.

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