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

Annotations already cover safety (readOnly, idempotent, non-destructive) and closed-world scope, so the bar is lower; the description still adds substantive context by naming the data source (UK Companies House, SH01 allotments and filed accounts), bounding scope to priced rounds and corporate-only shareholders, and promising provenance ('working') and filing links. 'Every priced round we can read' usefully signals possible coverage gaps, though no rate limits or failure modes are mentioned.

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?

Three tight sentences with no filler, and the payload scope is front-loaded before the source and guarantees. The first sentence is a dense comma-list that is slightly harder to parse than separate clauses would be, but nothing is wasted.

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 must convey the return shape, and it does so credibly: a company profile plus rounds, financials, shareholders, and website, each with provenance. The only material gap is the unaddressed boundary against sibling tools that return subsets of this same data.

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 and the schema description already covers it fully with format and examples (100% coverage), so the description carries no obligation to explain it. The description adds no additional meaning about the company number beyond what the schema states, which is the expected baseline.

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 names a specific resource (one company) and enumerates the payload: facts, priced rounds with workings and filing links, latest financials, corporate shareholders, and website. It is clear what the tool returns, but it never differentiates itself from siblings like get_company_rounds and get_company_financials, whose outputs it appears to aggregate.

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 and no mention of alternatives, despite substantial apparent overlap with get_company_rounds and get_company_financials. An agent must infer from the phrase 'One company' that this is the single-company aggregate lookup rather than a search tool.

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