lookup_by_identifier

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

With no annotations, the description fully discloses return shape (single entity with id, type, jurisdiction, identifier, risk), distinguishes two failure modes (400 for unsupported scheme, 404 for not found), and states that all schemes were production-tested. It also explicitly documents validation behavior (complete enum, hard-reject with 400).

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 but every sentence earns its place: purpose, usage, failure modes, and exclusions are each addressed. It is front-loaded with the core purpose and structured logically, avoiding redundancy despite 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?

Given the tool's complexity (11 schemes, two error modes, non-accepted identifiers) and no output schema, the description is remarkably complete. It covers return value shape, error handling, fallback guidance, and test validation date, leaving no major gap for an agent to misinterpret.

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%, so baseline is 3. The description adds value by explaining the complete accepted set, giving examples of non-accepted identifiers, and detailing error responses tied to parameters. However, much of the parameter detail (e.g., br-cnpj formats) is already in the schema, so the incremental addition is moderate.

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?

Clearly states it resolves an entity by strong external identifier, lists specific identifier types, and explicitly distinguishes from search_entities as fallback. The verb 'resolve' and resource 'entity' are specific, and it scopes to single entity results, differentiating it from sibling tools like lookup_company which uses name-based lookup.

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?

Provides explicit when-to-use ('when you already hold a registry id'), when-not-to-use with fallback ('A 404 is a statement about the corpus, not about the tool — fall back to search_entities'), and names alternatives (search_entities for Cyprus ids). Also excludes unsupported identifiers (cy-reg, cusip) with concrete advice.

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