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

Annotations already mark this as read-only, idempotent, open-world, and non-destructive. The description adds substantial behavioral detail beyond that: graceful degradation when GLEIF/OpenFIGI are unavailable, explicit listing of unresolved identifiers, returning figi_candidates on ambiguity, labeling identifier sources, and cascading through multiple lookup endpoints. No contradiction with 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 the tool is genuinely complex with two entity types and several edge cases. It is front-loaded with purpose and usage, then structured around SUPPORTED TYPES. Some parenthetical asides could be trimmed, but most sentences carry disambiguation value; the final 'replaces 2-3 manual lookups' is the only clearly non-essential sentence.

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 tool with no output schema, the description explains key return behavior: unresolved identifiers are listed under unresolved, ambiguous FIGI matches yield figi_candidates, drug results include RxCUI/ingredient/brand and a citation, and enrichment failures degrade to EDGAR results. Combined with exhaustive parameter semantics and type coverage, an agent has enough to call and interpret 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?

Schema coverage is 100% and both parameters have descriptions, but the tool description adds critical guidance: for company, value accepts ticker, CIK, ISIN, or name; for drugs it accepts brand or generic; and for bonds it instructs passing the issuer exactly as printed without trailing security-class words. This goes well beyond the schema and materially reduces invocation errors.

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 specific verb and resource: resolve user-spoken names to canonical/official identifiers consumed by other tools. It includes concrete input examples, supported entity types, and clarifies that it handles non-equity instruments and ISIN-to-entity resolution, making it easy to distinguish from sibling tools like compare_entities or entity_profile.

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 an explicit directive: 'Use FIRST whenever you have a name but need an ID,' and provides numerous query patterns. It does not explicitly name alternative tools or state when not to use it, but the 'first step' framing and the ID-oriented purpose effectively communicate placement among siblings.

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