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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds real behavioral detail beyond that: model works without make, 48 vehicles per page plus live-count facets and total matches, and an unresolved ZIP is silently ignored rather than rejected.

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?

Three tight sentences, front-loaded with the core action, then behavioral notes, then routing to siblings. Every sentence earns its place with no redundancy.

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 return values need not be re-explained; the description still adds pagination and facet counts. Scope, pagination behavior, edge cases, and sibling routing are all covered for a zero-required-param search 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%, so the baseline is 3, but the description contributes edge-case semantics the schema doesn't emphasize cleanly: model is independent of make and ZIP is best-effort/ignored. That is genuine added value over the structured field descriptions.

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 (Search) and resource (CarMax used-car listing records) and enumerates the filter fields it accepts. It explicitly differentiates itself from sibling tools like carmax_vehicle, carmax_search_suggestions, and carmax_shop_by_brand.

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?

Names the alternatives and the condition that selects each: carmax_vehicle for a single listing, carmax_search_suggestions for typeahead, carmax_shop_by_brand for browsing brands. Almost 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.