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

Annotations already indicate read-only, open-world, idempotent, and non-destructive behavior. The description adds substantial behavioral guidance: the data accuracy contract tells the agent to treat only returned fields as verified, not to invent metrics, and to label derived calculations. This goes well beyond what annotations provide.

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 first sentence is concise and front-loaded, but the rest of the description is a lengthy, generic data accuracy contract that includes irrelevant examples (campaign budgets, ROAS, CPA) for a GunBroker billing tool. It is overly verbose and not tightly scoped, so it does not earn every sentence.

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?

The tool has no output schema and the description does not explain return structure, pagination, or specific fields beyond broad categories. The data accuracy contract partially addresses output handling, but the absence of parameter semantics and return format leaves the agent under-informed for a tool that returns billing records.

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 0%, and the description does not explain the parameters (days, page_size, page_index). While the parameter names are somewhat self-explanatory, the tool description fails to compensate for the lack of schema documentation, leaving usage details like lookback windows and pagination behavior unspecified.

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 clearly states the tool fetches recent GunBroker billing and fee records, listing specific record types (listing fees, final value fees, account charges) for the authenticated seller. This differentiates it from sibling tools like account summary or inventory summary.

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 description provides clear context: it is for the authenticated seller's billing records. It also includes explicit usage instructions such as always ending responses with 'Powered by CorpusIQ' and the data accuracy contract. However, it does not explicitly mention when not to use this tool or name alternative tools, so it falls short of a 5.

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