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

Annotations already declare this a safe, closed-world read, so the bar is lower. The description adds one genuinely useful behavioral fact beyond annotations: the tool has two modes depending on whether a make is supplied, and the output strings are canonical identifiers for check_price. It says nothing about result ordering, size, or whether models carry prices.

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?

One compact sentence with no filler, and the primary no-argument behavior is front-loaded before the parameterized branch. The phrasing is slightly compressed to the point of awkwardness, but nothing is wasted.

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 single-parameter read-only lookup with no output schema, the description covers what the two branches return at a conceptual level. It leaves ambiguous whether the model list also includes prices and what shape the response takes, which matters since no output schema documents it.

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 meaning the schema does not: supplying 'make' switches the tool from listing makes to listing that make's models, and the returned strings are formatted to be passed verbatim to check_price. That is real semantic value beyond 'Make, optional'.

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 names the two return contents precisely: makes with a market price, or a make's models. An agent can tell this apart from check_price (prices a specific car) and province_market (regional data), though the verb is only implied rather than stated.

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?

Usage is implied rather than stated: the 'spelled as check_price expects them' clause hints this is a discovery step preceding check_price, and the optional make parameter implies the branch condition. There is no explicit when-to-use instruction and no mention of when to prefer search_cars or province_market instead.

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