YardStock NZ Vehicle Listings

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

With no annotations, the description carries the full burden of behavioral disclosure. It provides no information about side effects, return format, external calls, authorization requirements, or what 'Call first' means, so the agent cannot predict tool behavior.

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 very brief, which is good, but the second sentence 'Call first' is cryptic and does not earn its place. The structure is fragmented and lacks a clear declarative explanation of the tool.

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?

The description is far too incomplete for an agent to invoke correctly. It has no params, no output schema, no clear semantics, and ambiguous instructions, so the agent cannot know what input it needs or what result to expect.

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?

The input schema has zero parameters and 100% coverage, so the baseline for parameter semantics is 4. The description adds no parameter detail, but none is needed since no parameters exist; however, it also fails to explain how the tool knows which stock product is referenced.

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 is phrased as a question, not a clear verb+resource statement, and it does not say what 'coverage' actually does or returns. It could mean a person responsible, a coverage area, or a status, and it does not distinguish itself from siblings get_listing or search_stock.

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?

No guidance is given for when to use this tool versus get_listing or search_stock. The instruction 'Call first' is ambiguous and does not clarify prerequisites, alternatives, or context.

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

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

With no annotations provided, the description carries the full burden of behavioral disclosure. 'Fetch' implies a read-only retrieval, but the description does not disclose error behavior, return format, authentication requirements, rate limits, or any side effects. This is a minimal statement with no depth beyond the core action.

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 one concise, front-loaded sentence ('Fetch one listing by its source_url.') with no redundant words. Every term earns its place, making it an exemplary concise structure.

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?

The tool has no output schema and no annotations, so the description should explain what a successful result looks like and how failures surface. It only states the input and a vague output ('one listing'), leaving an agent without enough context to handle missing records, response shapes, or when this tool is preferable to sibling tools.

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?

The schema has zero description coverage for the source_url parameter, but the tool description says 'by its source_url,' which clarifies that source_url is the unique identifier used to select the listing. This adds meaningful semantics beyond the raw schema and fully compensates for the single parameter's lack of description.

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 states a specific verb ('Fetch') and resource ('one listing') plus the identifying key ('source_url'), making the tool's purpose clear. It does not explicitly distinguish itself from siblings like coverage or search_stock, but the phrasing narrows the action to a single-record lookup.

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?

No guidance is given about when to use this tool versus the alternatives (coverage, search_stock). The only implied use case is 'when you have a source_url and need one listing,' but no explicit conditions, exclusions, or alternative routing are provided.

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

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

With no annotations provided, the description must disclose behavioral traits. It implies a read-only search via the word 'Search', but does not describe what 'live' means relative to ingestion, whether results are paginated, or any other operational behavior. The bare statement adds little beyond the tool's obvious purpose.

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 exceptionally concise, using two short sentences with no filler. The core action and resource are front-loaded, and the 'Not Trade Me' clarification earns its place by narrowing scope. Every word contributes.

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 nine optional parameters, zero annotation coverage, and no output schema, this 13-word description is severely incomplete. It fails to explain return values, filter behavior, limits, or data freshness, leaving an agent without enough context to invoke the tool 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?

Schema description coverage is 0%, so the description must compensate by explaining parameter meaning. It does not mention any of the nine parameters (city, fuel, make, limit, model, year_min, price_max_nzd, etc.), leaving filter semantics entirely undocumented for the agent.

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?

Description states a clear verb ('Search') and specific resource ('live used cars on ingested NZ dealer yards'), distinguishing it from broader marketplaces like Trade Me. However, it does not explicitly differentiate from sibling tools 'coverage' and 'get_listing', so it misses the explicit sibling distinction that would earn a 5.

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 phrase 'Not Trade Me' gives a single exclusion but provides no context on when to use this tool versus siblings 'coverage' or 'get_listing'. No mention of scenarios, prerequisites, or alternatives, leaving the agent without actionable routing guidance.

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