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

Beyond the read-only/idempotent annotations, the description discloses many behavioral traits: graceful degradation if GLEIF/OpenFIGI is unavailable, explicit unresolved identifiers instead of silent omission, source-labelled identifiers, candidate lists on ambiguous matches, and internal cascading through multiple lookup endpoints. This is rich, non-obvious behavior that an agent would not otherwise know.

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 user phrasings and the central 'Use FIRST' directive, and almost every clause carries useful information. However, it is extremely dense, with long parenthetical chains and a few repetitive points that could be tightened without losing meaning. It is well-structured for the complexity but not maximally concise.

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 thoroughly: identifier labels, unresolved fields, figi_candidates on ambiguity, RxNorm citation format, EDGAR fallback, and ISIN-to-LEI behavior. Both supported types and all accepted value forms are covered, and the graceful degradation note addresses failure modes. Nothing an agent needs to call this 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 already 100%, and the description and value parameter description add crucial semantics: accepted input forms (ticker, CIK, ISIN, name, brand/generic drug name), the ENTITY NAME ONLY restriction, and a concrete warning against including security-class trailing words in bond issuer lookups. The type enum is also expanded with detailed behavior per type.

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 by giving concrete user phrasings ('What's the ticker for…' / 'find the CIK for…') and then states a precise verb-resource pair: resolve a user-spoken name to canonical/official identifiers that other tools require. It explicitly distinguishes two supported types (company and drug) with detailed cross-source identity coverage, making it clear this is an entity-identifier resolution tool rather than a profile, comparison, or research tool.

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 usage guidance: 'Use FIRST whenever you have a name but need an ID.' It also clarifies when resolution should not assert an answer (ambiguous instrument names return figi_candidates) and when enrichment degrades gracefully. It does not name sibling alternatives or state explicit when-not-to-use conditions, so it falls short of a full 5, but the context is clear.

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