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

Annotations already say readOnlyHint, openWorldHint, idempotentHint are true and destructiveHint is false. The description adds substantial behavioral context beyond these: it cascades through multiple lookup endpoints, LEI/FIGI enrichment degrades gracefully if upstream sources are unavailable while EDGAR identifiers still return, and unresolved identifiers are reportedly stated explicitly. This gives the agent realistic expectations about partial results and internal behavior without contradicting the annotations.

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 long and dense, but most sentences earn their place: the example query patterns, supported types, return fields, and input caveats are all actionable. The structure is front-loaded with the 'Use FIRST' guidance and supported types. It loses a point because the company-type explanation is heavily nested with parentheticals and could be more scannable, though it is not padded with filler.

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-parameter tool with no output schema, the description is remarkably complete. It covers accepted inputs, per-type return contents, special cases like non-equity instruments and ISIN-to-LEI resolution, graceful degradation when enrichment sources fail, and a pitfall that could otherwise cause failed lookups. There is no obvious missing context an agent would need to call this tool 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 description coverage is 100%, the description adds considerable meaning beyond the schema. For the 'value' parameter it gives concrete examples ('AAPL', '0000320193', 'ozempic') and a crucial semantic rule: pass the entity name only, never the full noun phrase, because the FIGI lookup matches instrument names. For 'type' it explains what each type returns (CIK/ticker/LEI/FIGI for company, RxCUI/ingredient/brand for drug). This materially improves correct invocation.

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 precise purpose: 'resolve a user-spoken NAME to the canonical/official identifiers other tools require as input.' It is immediately differentiated from sibling tools by saying 'Use FIRST whenever you have a name but need an ID,' and it enumerates concrete query examples and supported entity types, so an agent cannot confuse it with 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?

The description gives clear, explicit usage guidance: 'Use FIRST whenever you have a name but need an ID,' and explains which input forms work (ticker, CIK, ISIN, company name, drug brand/generic). It provides rich context and even warns about a common misuse (passing the full noun phrase instead of the issuer name). However, it does not explicitly state when not to use it or name a direct alternative tool, so it stops short of full when/when-not coverage.

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