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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety profile. The description adds what data the listing contains, which is useful, but says nothing about auth, rate limits, or the transfer-fee pricing context that store_id implies. No contradiction with annotations.

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 tight sentences: the payload is front-loaded, followed by the routing guidance to sibling tools. Zero wasted words.

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, return values need not be explained, and the schema fully documents parameters. The description covers purpose and tool routing adequately; only minor behavioral context (e.g., pricing/transfer-fee implications of store_id) is left to the schema.

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 100%, so both stock_number and the non-obvious store_id defaulting behavior are fully documented in the schema. The description adds no parameter-level meaning beyond what the schema provides, so baseline 3 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?

States a specific verb ('Fetch') and resource ('a CarMax vehicle listing') plus the exact payload (specifications, equipment, warranties, history). It also names the sibling tools it is not, so an agent can distinguish it from carmax_search and carmax_vehicle_recommendations without opening schemas.

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?

Explicitly tells the agent how to obtain the required stock_number ('Use carmax_search to find a stock number') and points to carmax_vehicle_recommendations for comparable vehicles. It gives clear usage context but does not spell out when-not to use it or prerequisites beyond parameter sourcing.

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