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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses a cost of 1 credit and enumerates the categories of returned data, including overdue flags, charges, and insolvency flags. However, it does not state error behavior, authentication/rate-limit constraints, or whether missing data is returned as null versus omitted.

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 a single dense sentence with the resource and scope front-loaded, followed by the key returned fields and cost. Every element is useful for selection and invocation, with no redundant wording.

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 one-parameter read lookup with no output schema, the description is largely complete: it defines the resource, lists major returned categories, and discloses the credit cost. It remains slightly incomplete because it omits company-number format expectations and explicit routing guidance among related company tools.

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 description coverage is 100%, so the single parameter is already documented as a required company number. The description only restates that lookup is by company number and adds no format guidance such as expected length, prefix, or examples. Baseline 3 is appropriate because the schema does the substantive work.

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 the specific resource and scope: a full Companies House profile keyed by company number. It enumerates returned data such as status, SIC codes, registered office, accounts dates, charges, and insolvency flags, making the tool's purpose clear. It does not explicitly contrast itself with siblings like company_search, company_filings, or company_officers, so it falls short of a 5.

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?

There is no explicit when-to-use guidance, no prerequisites, and no named alternatives. An agent can infer that this is for retrieving a company's full profile, but the many related sibling tools are not addressed. It does not mention using company_search first if the company number is unknown.

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