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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context that annotations cannot carry: per-company pricing ($0.002) with no start fee, which matters for call-volume decisions, and that results come back as 'clean JSON'. It does not mention rate limits, upstream Companies House freshness/latency, or pagination behavior.

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 core capability and scope are front-loaded in the first clause, and the text is short. The price is stated twice ('$0.002 per company, no start fee' and then 'Price: $0.002 per `company`.') and the audience list is longer than needed, which is minor waste.

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 read-only, fully-schema-documented, six-parameter list tool with no output schema, the definition covers scope, filters, default date window, output format and cost. Nothing critical to invoking it correctly is missing; a field-level return description would be nice but is not required for correct selection.

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 the schema carries the parameter documentation and a baseline of 3 applies. The description adds one thing the schema does not: that omitting dates yields yesterday's incorporations, which defines the default behavior of incorporatedFrom/incorporatedTo that have no schema default. It restates the filter dimensions only at a high level.

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 every new UK company incorporated') plus the default scope ('yesterday (or on any date range)'), the output shape ('clean JSON'), and the filter dimensions (SIC code, location, company type). An agent can tell this apart from siblings like company_check or sec_company_screen without opening the schema.

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 audience list (sales teams, lead-gen agents, accountants, banks, insurers, web agencies) implies when the tool is useful, and 'yesterday (or any date range)' signals the default call pattern. However, there is no explicit when-not guidance and no named alternative among the siblings for adjacent needs such as company_check or company_accounts.

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