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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds genuinely new behavior: collector status distinguishes an inactive feed from observed events, no photos or dealer text are included, 'delisted' means only that the listing was no longer observed rather than a completed sale, and the tier-based result caps (10 events, no paging on free vs. 200 with cursors on paid). These are exactly the caveats an agent needs before interpreting results.

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?

Four dense sentences, each carrying distinct information: scope and filters, the collector-status caveat, the delisted semantic caveat, and the pagination limits. The most important scoping information is front-loaded and no sentence is 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?

There is no output schema, so the description compensates by enumerating the returned fields (VIN, price, mileage, dates, source, link) and by stating the paging limits. Combined with annotations covering the safety profile, an agent has everything needed to call and interpret this read-only list 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?

With 0% schema description coverage across 9 params, the description has to carry the load, and it largely does: it names the filter axes (vehicle, event type, date) and explains cursor/limit behavior through the paging and per-call caps. It does not spell out the make/model/year breakdown, the default limit of 50, or date format, so a small gap remains.

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 (List) and resource (observed dealer listing changes), enumerates the event types (new, price drop, relisted, delisted), and lists the returned fields. Nothing in the sibling set (compare_vehicles, recall_changes, vehicle_risk) covers listing events, so the tool is trivially distinguishable.

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 through the filter axes ('filtered by vehicle, event type or date') and the free-tier/paid-tier call limits, which tell the agent when it can and cannot page. However, it never names an alternative tool or states an explicit when-not-to-use condition, leaving the agent to infer selection.

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