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

With no annotations, the description carries the behavioral burden and does substantial work: it discloses that the source is verified UK dealers, that prices are live/current, that mileage is in miles, that each result includes a canonical URL, and that this source is one of the few machine-readable options due to robots.txt blocking elsewhere. It stops short of describing result structure or pagination behavior, but for a search tool this is solid.

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?

Three sentences front-load the core purpose, then add output format and usage context. It is appropriately sized, with only minor redundancy between 'live', 'real', and 'actual cars'.

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 an 11-parameter tool with no output schema and no annotations, the description covers the key facts an agent needs: source, data quality, units, URL return value, and when to use it. The main omission is a clearer picture of the full result payload and default ordering/pagination, but these are not critical for invocation.

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 82%, so the schema already documents most parameters with examples. The description reinforces the GBP unit for prices but does not add meaning for the undocumented max_year/min_year parameters, so it stays at the baseline without compensating.

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 begins with a specific verb and resource: 'Search live used cars for sale from verified UK dealers on Autoza', with concrete output details (prices in GBP, mileage in miles). It clearly differentiates itself from sibling tools like get_uk_price_guide by emphasizing actual cars currently for sale.

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 gives an explicit trigger: 'Use when someone wants to find, browse or compare actual cars currently for sale in the UK.' It does not explicitly name when-not-to-use cases or point to alternative siblings, though the use-case sentence makes the boundary clear.

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