compare_vehiclesCompare two to four distinct returned listing IDs using current inventory facts. Missing data is not an assessment of the vehicle.
| Name | Required | Description | Default |
|---|---|---|---|
| priorities | No | Shopper priorities, up to eight. | |
| listing_ids | Yes | 2-4 exact IDs returned by shop_vehicles. |
| Name | Required | Description | Default |
|---|---|---|---|
| compared | Yes | ||
| vehicles | Yes | ||
| recommendation | Yes | ||
| missing_listing_ids | Yes |
Changes observed during successful MCP inspections.
Output schema / properties / vehicles / items / properties / listing / properties / currencyAdded value: +{
+ "enum": [
+ "USD",
+ "CAD"
+ ],
+ "type": "string"
+}Output schema / properties / vehicles / items / properties / listing / properties / location / properties / country / constRemoved value: -"US"Output schema / properties / vehicles / items / properties / listing / properties / location / properties / country / enumAdded value: +[
+ "US",
+ "CA"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile, and the description adds useful behavioral context: comparisons use current inventory facts and missing data should not be interpreted as a negative assessment. It does not contradict the read-only, idempotent 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 short sentences, front-loaded with the core action and followed by a relevant interpretation caveat. There is no wasted wording.
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 rich annotations, complete input schema, and existing output schema, the description is nearly complete. The main remaining gap is that it does not explicitly route agents to or away from sibling tools, though the schema points to shop_vehicles.
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 coverage is 100%, so the baseline is 3, but the description adds a meaningful constraint by requiring distinct listing IDs, beyond the schema's minItems/maxItems. The optional priorities parameter is left to the schema description, which is adequate.
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 gives a specific verb and resource: compare two to four listing IDs using current inventory facts. It clearly implies a multi-vehicle comparison rather than a single-vehicle lookup, though it does not explicitly name sibling tools like get_vehicle or shop_vehicles.
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 establishes a clear usage context: compare 2-4 distinct listing IDs that were already returned, using current inventory facts. It does not explicitly state when to prefer this over get_vehicle or shop_vehicles, but it does not introduce misleading exclusions either.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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