Compare carts

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 adds genuine behavioral context beyond that: it reports the sorting order (cheapest to most expensive) and highlights derived values like 'missing amount' that the agent can rely on for comparison reasoning. It does not mention failure modes when a retailer cart is empty or unreachable, which is a gap for an open-world read.

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 sentences, zero filler: the first front-loads what is read and what fields come back, the second gives the ordering guarantee. Nothing is repeated from the name or schema.

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?

An output schema exists, so the description needn't enumerate return values, and annotations cover the read-only/open-world profile. What's missing is scope framing — which retailers are included, and what happens when a cart is missing or a retailer has no slots — which matters for an open-world comparison tool.

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 100% and the single 'mode' parameter is documented with an enum (drive/delivery) and a description, so the schema carries the semantics. The description never mentions fulfilment mode, so it adds nothing about how drive vs delivery changes which carts are read or what slots are returned — baseline 3 is appropriate.

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 ('reads') and a clearly scoped resource ('each retailer's cart'), which implicitly distinguishes it from the singular get_cart sibling by emphasizing cross-retailer aggregation. It also enumerates the fields read (total, lines, minimum order, missing amount, next slots). It stops short of naming the sibling it contrasts with, so the differentiation is inferential rather than explicit.

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?

No explicit when-to-use statement or alternative is named. The plural 'each retailer's cart' and the sorting hint imply the tool is for cross-retailer comparison rather than inspecting one cart, but the agent must infer that get_cart is the single-retailer alternative.

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