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

Beyond the annotations (readOnly/openWorld/idempotent/non-destructive), the description reveals key runtime behavior: ambiguity returns `figi_candidates` rather than asserting, unresolved identifiers are listed under `unresolved` instead of omitted, enrichment degrades gracefully when GLEIF/OpenFIGI are down, and each call cascades internally through several endpoints.

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 dense and heavily parenthetical, and some phrases are editorial ('which is the correct answer...'), but it is well front-loaded with the purpose and use trigger, then organizes the two supported types with enough detail to justify its length.

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 still explains the main return fields (CIK, ticker, company_name, LEI, FIGI, RxCUI, ingredient, brand, citation), the ambiguity fallback, the `unresolved` field, and graceful degradation. This is sufficient for an agent to call the tool and interpret common outcomes correctly.

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?

Although schema coverage is 100%, the description substantially extends the schema: it lists accepted input forms for `value` (ticker, CIK, ISIN, company name, brand/generic), explains the ISIN-to-LEI path for non-US issuers, and gives explicit formatting guidance such as passing the issuer exactly as printed and excluding trailing security-class words.

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 phrasings ('What's the ticker for…' / 'find the CIK for…') and immediately states the verb-resource pair: 'resolve a user-spoken NAME to the canonical/official identifiers other tools require as input.' It also scopes supported types ('company', 'drug') and contrasts with downstream tools, making it easy to distinguish from siblings like entity_profile or compare_entities.

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 an explicit trigger: 'Use FIRST whenever you have a name but need an ID,' and clarifies that it 'replaces 2-3 manual lookups.' It does not name a specific alternative to switch to when the user does not need an ID, so there is a slight gap in when-not-to-use guidance.

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