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

Beyond the annotations, it discloses that this sends a real message to a real dealership on behalf of the user, only dealers who have joined iwant.fyi receive it, and unregistered dealers result in a needs_dealer response with nothing sent. It also states no personal user details ever reach the dealer, which is important behavioral and policy context.

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?

The description is a tight, front-loaded paragraph where every sentence contributes: purpose, triggering conditions, required payload, eligibility/failure mode, privacy, and consent requirement. There is no filler or redundant phrasing.

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?

Given the external side effect and the five parameters, the description covers the critical operational and consent obligations: asking before calling, the eligibility failure path, and the privacy guarantee. The output schema exists, so return-value detail doesn't need to live in the description.

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 the schema already documents all five parameters. The description adds a useful pointer that listing_id comes from demand.find_vehicle and that the message should be the user's own words, but it doesn't add per-parameter semantics beyond that, so the baseline of 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?

The description opens with a specific verb and resource: 'Ask a specific seller to answer the user about one car from demand.find_vehicle.' It also enumerates exact user intents that should trigger the call, making it easy to distinguish from siblings like demand.ask or demand.find_vehicle.

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?

The description gives clear trigger conditions ('wants that one', 'out-the-door price', 'still available', 'put in touch') and an explicit consent rule: 'Ask the user before calling.' It doesn't explicitly name when-not-to-call or alternative sibling tools, but the usage direction is strong enough to be near-explicit.

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