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

With no annotations, the description carries the full behavioral burden and does substantial work: it discloses that the response payload varies by authentication (open fields plus a role count without a subscription key, full roles/contacts/sources/verification note with one). It omits failure behavior for an unknown id and any permission/rate context.

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?

A single sentence, front-loaded with the subject ('One firm by its registry id') followed by the conditional payload split. Every clause conveys new information; nothing is padded or repeated from the schema.

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 correctly compensates by enumerating the returned fields under both auth states, which is exactly what an agent needs to reason about results. The remaining gap is error/not-found behavior for an invalid id.

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?

There is a single parameter with 100% schema description coverage, so the schema already explains that id is the registry id from search_registry. The description adds no syntax, format, or validation detail beyond that, making the 3 baseline appropriate.

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?

States a specific verb and resource: fetch exactly one firm identified by its registry id. The singular 'one firm' implicitly contrasts with the sibling search_registry, though it never names the sibling or explicitly says 'use this instead of search when you already have an id'.

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?

Usage is implied rather than stated: the schema note 'as returned by search_registry' and the singular resource suggest the search-then-fetch flow, but the description gives no explicit when-to-use, when-not-to-use, or alternative routing.

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