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

Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds value by specifying the data returned (VIN, price, miles, dealer info, Carfax status, days on market) and the source (MarketCheck). It also mentions radius limits on free tier, which is useful beyond 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?

The description is three sentences, front-loaded with the action and key filters. Every sentence adds essential information with no fluff. Highly efficient.

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 complexity (12 parameters, high schema coverage, output schema exists, annotations provided), the description is complete. It covers what the tool does, what it returns, and key constraints. The agent has sufficient information to use it correctly.

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?

Input schema has 100% coverage with descriptions. The description reiterates key parameters (make, model, year, price range, miles, zip, radius) and adds context like US-only and free tier radius limit (max 100 miles). This adds marginal value over the schema.

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 clearly states the verb 'Search' and the resource 'US car listings'. It specifies millions of active listings and filters by make, model, year, etc. This distinguishes it from siblings like 'vehicle.carmarket.listing' which likely handles individual listings.

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 implies usage for searching car listings in the US but does not explicitly state when to use this tool versus alternatives like 'vehicle.carmarket.listing' or 'vehicle.vin.decode'. No guidance on when not to use it is provided.

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