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 structurally. The description adds meaningful context beyond that: the statutory source and licence, the 1-credit cost, and the fact that a name input also returns otherMatches (possible duplicate reporting companies).

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 purpose is front-loaded in the first sentence, with the returned fields and cost following compactly. The em-dash field list is dense but informative; 'a plain reading for suppliers' is slightly vague phrasing but does signal an interpretive summary field.

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 usefully enumerates what comes back: average days to pay, share paid late, terms, trend, benchmark, plain reading, and otherMatches. That is enough for an agent to call it correctly; minor gaps are error behavior for companies with no reports and pagination/limits, which are unlikely to matter for a per-company lookup.

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% for the single company parameter, so the baseline is 3. The description goes beyond it by clarifying the behavioral difference between passing a number versus a name, since a name triggers the additional otherMatches result.

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-like outcome and resource: how fast a large UK company pays its suppliers, sourced from statutory Payment Practices reports. It clearly distinguishes itself from generic company-data siblings, though it does not explicitly differentiate from the overlapping late_payment and will_they_pay tools.

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 by the content summary — you call it when you need supplier payment-speed data for a UK company with filed reports. There is no explicit when-to-use framing, no mention of when it is inappropriate, and no named alternative among the many payment-related siblings.

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