Price a basket

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

Annotations already declare readOnly/idempotent/openWorld, and the description adds substantial context beyond them: no persistence, no authentication, no order placement, shipping exclusion, and the max_count/over_max_count refusal behavior. These are exactly the side-effect and constraint details an agent cannot infer from structured fields.

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 outcome, then constraints in short declarative sentences. The parenthetical asides ('it needs a logged-in address') are slightly chatty but each sentence carries useful information, so little is wasted.

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?

With an output schema present and 100% schema coverage, the description need not explain return values, and it correctly focuses on the non-obvious: guest mode, shipping exclusion, quantity limits, and the dedupe constraint. Nothing needed to call it correctly is missing.

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%, so the baseline is 3, but the description adds genuine meaning: it explains what max_count and over_max_count mean in the response and clarifies the one-entry-per-seller_item_id rule, which shapes how the items array must be constructed.

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 and resource: 'Get the exact total for a set of seller items', and enumerates what the total includes (discounts, insurance, quantity limits, cash vs installment). An agent knows precisely what this computes, though it never explicitly names which sibling (e.g. tl_compare, tl_find_cheapest) it replaces.

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 concrete operating context: prices as a guest, nothing saved, no login, no order, shipping excluded because an address requires login. It also constrains invocation ('each seller_item_id may appear once: compare cash and installment in separate calls'), which is real usage guidance, though no alternative tool is named.

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