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

With no annotations, the description carries the full burden and does well: it discloses provenance ('Sourced ... no LLM fiction'), enumerates collected data categories, and surfaces a per-call cost ($0.25 USDC), which matters for an agent deciding to invoke. It stops short of stating whether the charge applies on failure, latency expectations, or error 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?

Front-loaded with the routing condition and the exclusion, then the data scope, then the example and cost — a sensible priority order. The dash-separated source list is dense but each item adds signal; only the fragmentary phrasing costs it a point.

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 what to pass, what comes back at a category level, what it costs, and when not to use it. A short note on output shape or failure/payment semantics would make it fully complete.

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% and the single 'domain' property is undocumented, so the description must compensate. The phrase 'from its website domain' plus the example {domain:"stripe.com"} conveys the expected bare-domain format (no scheme or path), which is the key ambiguity for this parameter.

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 ('researching a company from its website domain') and immediately scopes it away from the sibling 'uk_company' family by name, so an agent can discriminate without opening a 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?

Gives an explicit when-to-use clause, an explicit when-not ('not UK Companies House'), a named alternative ('Prefer uk_company* for UK filings'), and a concrete invocation example. Nothing is left to inference about routing.

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