List sellers

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

Annotations only declare readOnlyHint=true; the description adds two genuinely non-obvious behavioural facts — that results include prices and that at least one entry is a paid placement ('a featured seller paid for its place'), which warns the agent about ranking bias. That paid-placement disclosure is exactly the kind of context structured fields cannot carry.

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?

Two short sentences, front-loaded with the eligibility constraint and followed by the disclosure that matters most for trusting the ordering. No filler and nothing a reader would want moved earlier.

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 zero-parameter read-only list with no output schema, the description covers who appears in the list, that prices are attached, and the sponsored-ordering caveat. It stops short of sketching the per-seller record fields, which is the only remaining gap — minor, since there is no output schema promising that detail elsewhere.

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?

The tool takes no parameters, so there is nothing for the description to disambiguate. The baseline for a zero-parameter tool applies.

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?

Names the resource precisely — sellers available for credit payment — and adds that prices are included. It doesn't name or exclude the siblings credit_status / pay_with_credit, so the agent still has to infer the relationship, but the noun phrase is specific enough to distinguish this from a generic seller lookup.

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?

There is no explicit when-to-use or when-not-to-use statement. The phrase 'sellers you can pay on credit' implies this is the discovery step preceding pay_with_credit, and the absence of parameters implies a full-list read, but the agent must infer all of that rather than being told.

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