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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds meaningful behavioral context beyond them: no API key needed, instant responses, curated-database coverage limits, and the important no-match-is-a-signal behavior. This goes beyond what annotations alone convey.

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 compact and front-loaded with key decision-relevant facts: free, instant, single-platform lookup, coverage scope, and follow-up behavior. Every sentence adds useful information without redundancy or filler.

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?

For a simple 2-parameter lookup with annotations covering safety, the description is largely complete: it lists the returned data, defines coverage, and explains the no-match case. The absence of an output schema is partially compensated by the output list, but exact return formatting or field structures are left unspecified.

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 baseline is 3. The description reinforces that mileage is used for valuation ('private-party value at a mileage') but does not add new constraints, formats, or clarifications beyond the schema. It provides no extra semantic value for the parameters.

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 uses a specific verb and resource: 'Look up one platform in BuyerAware's curated database' and enumerates the returned outputs (risk score, verdict, trap, value, cost). It distinguishes itself from siblings by explicitly defining its 47-platform scope and by noting that no match should be followed up with analyze_listing.

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?

It clearly gives context for when to use the lookup and explicitly names analyze_listing as the follow-up for platforms outside the 47 covered. It does not explicitly exclude get_verdict or tank_alternatives, but the lookup-vs-listing distinction is still clear enough for an agent.

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