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

With no annotations, the description carries the full burden, and it does disclose the price ($0.65 USDC), the bundling rule, and the auto-attachment trigger ('.uk TLD or CH number detected') — useful non-obvious behavior. However, it never states what happens when no UK signal is present (implied by uk_included, but unstated), whether the charge still applies, or any rate/auth constraints, so the mutation-and-billing profile is only partially covered.

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?

Front-loaded with the use case, then the auto-attach rule, then a concrete input/output example — an efficient ordering. The price is stated twice ($0.65 vs $0.75, then $0.65 USDC), which is mild redundancy in an otherwise tight description.

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 tool with no annotations and no output schema, the description covers purpose, cost, conditional behavior, and even the return shape ({company, uk, uk_included}). The main omission is what the response looks like when UK data is not included.

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 0% for the single 'domain' parameter, so the description must compensate. The example {domain:"tesco.com"} shows the expected value shape — a bare domain, not a URL — which is genuinely helpful, but it does not clarify edge cases such as subdomains, paths, or scheme prefixes.

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 both resources precisely: 'website company research' plus 'UK Companies House pack in one call', which tells an agent this is the combined bundle versus the separate company_research / uk_company siblings it alludes to via '$0.75 separate'. It stops short of naming those siblings explicitly, so an agent must infer which two tools this replaces.

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?

'Use this for website company research + UK Companies House pack' gives a clear selecting condition, and the price comparison against buying separately reinforces when this beats the alternatives. There is no explicit when-not guidance (e.g., use uk_company_lite if you already know the CH number), so the routing logic is only half-specified.

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