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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: it discloses the exact field set returned and flags that some values (company_age_years, accounts.overdue) are derived/enriched rather than raw API output, which tells the agent results may differ from Companies House directly.

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?

Two sentences, no filler. The first front-loads the action, scope, and identifier; the second handles return values. Every clause earns its place.

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 does the heavy lifting by enumerating return fields and noting derived values, which is what an agent needs to interpret results. The only gap is failure behavior for unknown or malformed company numbers (e.g., not-found handling), which the description does not mention.

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 only one parameter and the schema documents it fully (100% coverage, including the pattern and the zero-padding example for '00445790'). The description reinforces that the input is a Companies House number but adds no format or edge-case detail beyond the schema. Baseline 3 is appropriate when the schema carries the semantics.

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 ('Get an enriched profile for a UK company') and pins the identifier to a Companies House number, which immediately separates it from siblings like get_financials, get_directors, or get_psc. The enumeration of returned fields (status, SIC codes, accounts status, derived fields) further confirms this is the general profile retrieval 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 explains what the tool returns but never says when to choose it over get_financials, get_directors, get_compliance, or search_company. The only comparative hint is that derived fields are 'not available from the raw Companies House API', which is about the upstream source, not about tool selection. No exclusions or prerequisites are given.

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