Brands, models and trims

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real behavior: the 25-match cap and the enumeration semantics of each argument combination. It also discloses the lexical shape of returned values (brand, brand,model, brand,model,trim), which is exactly what an agent needs to reuse the output elsewhere.

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 short sentences with the cross-tool purpose front-loaded, followed by argument behavior and value format. Minor awkwardness in 'Give query to find matches' but no wasted content.

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?

No output schema exists, so the description carries the burden of describing returns, and it does so via the value-format convention and the 25-item cap. For a 3-optional-parameter lookup tool this is nearly complete; only pagination/truncation handling beyond the cap is unstated.

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 a 3 is the baseline, but the description adds meaning beyond the schema by stating what happens when brand and query are both omitted (list all brands) and how the returned strings encode brand/model/trim. The vehicle_type note ties the enum to the sibling tool that consumes those values.

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 and resource ('look up the brand, model and trim values') and immediately scopes it as the value-resolution companion for ba_search, ba_market_stats and ba_new_prices. An agent can tell this apart from ba_filters or ba_car_specs without opening the schema.

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?

Clearly explains the three modes: query finds up to 25 matches, brand lists that brand's models and trims, neither lists all brands. It also routes motorcycle/truck lookups explicitly. It stops short of saying when to call this versus ba_filters or ba_price_list, so it is clear context without explicit exclusions.

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