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

The description is highly transparent about behavior beyond the annotations: it explains the cross-source identity spine, source-labelled identifiers, explicit unresolved handling, non-assertion on ambiguous matches, ISIN-to-LEI resolution, and graceful degradation when GLEIF/OpenFIGI are unavailable. These behaviors are consistent with the readOnly, openWorld, and idempotent annotations. This is exemplary disclosure of internal behavior and failure modes.

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, with nested parentheticals, but nearly every clause carries load-bearing detail and the SUPPORTED TYPES structure keeps it navigable. It is front-loaded with the core rule ('Use FIRST whenever you have a name but need an ID') before diving into edge cases. A slightly tighter structure would improve readability, but the length is justified by the tool's complexity.

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: figi_candidates on ambiguity, an explicit unresolved field, source-labelled identifiers, RxNorm citation, and graceful degradation. It also covers major edge cases like non-equity instruments, non-US issuers, and multi-match situations. Given the tool's complexity, the description is complete enough for an agent to invoke it correctly without additional lookups.

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 the schema already provides 100% description coverage, the tool description adds crucial semantic constraints: pass only the entity name, never the question's full noun phrase, with the 'NEW YORK ST DORM AUTH' example illustrating the failure mode. It also clarifies per-type input formats (ticker, CIK, ISIN, brand/generic drug names) and how ISINs map to legal entities. This materially enhances agent understanding beyond the schema.

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 operation: resolving a user-spoken name to canonical/official identifiers that other tools require, backed by concrete examples and supported types. It distinguishes itself from generic lookups by enumerating the output identifiers (CIK, LEI, FIGI, RxCUI) and even clarifies that ticker-less instruments resolve here. This goes well beyond the name and title.

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 rule: 'Use FIRST whenever you have a name but need an ID,' and details accepted input forms, entity types, and ambiguity behavior. It also covers edge cases such as unresolved identifiers and source unavailability, which help an agent decide to use the tool. However, it does not name alternative sibling tools or explicitly state when not to use it, so exclusion guidance is implicit rather than direct.

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