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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description goes beyond that by disclosing the cost model (3 credits per result, 75 per full page, no charge on empty results) and the 25-result cap, which annotations cannot express. It still does not describe the shape of returned company records, so it is not fully rich.

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-loads the capability, then routes to the alternative, then states the filter requirement and cost. Every sentence carries distinct information (prerequisite, cap, pricing) with no filler.

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 an 8-parameter, zero-required search tool with no output schema, the description covers usage, prerequisites, alternatives, result cap, and billing. The only material gap is what fields the returned company records contain, which an agent would need before chaining into enrichment.

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 50%, and the description compensates by enumerating every filter and adding format meaning the schema lacks: ISO-2 country codes with examples (SA, AE, QA), employee_range example '51-200', and the constraint that at least one filter must be supplied. It does not clarify city/industry/keyword matching semantics or whether filters AND together, leaving some ambiguity.

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?

Opens with a specific verb+resource+scope: 'Finds companies that match filters and returns up to 25 results.' It explicitly distinguishes itself from the closest sibling by both naming apione_company_enrich as the enrichment follow-up and stating 'Not for looking up one known company (use apione_company_enrich).'

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 explicit when-to-use ('build a prospect list when you do not have domains yet'), the follow-on tool, a hard prerequisite ('Give at least one filter'), and a when-not-to-use case pointing to the alternative. Nothing is left to inference.

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