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

With no annotations, the description carries the full burden, and it does disclose one meaningful behavior: brands without active deals are excluded and results carry deal counts. It says nothing about whether filters apply to the deals being counted, result ordering, size limits, or read-only/rate-limit characteristics.

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, zero padding, with the core scope ('currently have active deals, with deal counts') front-loaded before the filter note.

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 9-parameter tool with no annotations and no output schema, the description should clarify the return shape (brand plus count, likely an array) and confirm that filters restrict the deals counted rather than the brands listed. The existing text covers intent but leaves those operational questions open.

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 78%, so the schema already documents fuels, price bounds, countries, mileage, discount, and price-dropped. The description adds only a cross-reference ('same filters as search_deals'), which helps an agent borrow semantics but does not explain how the filters scope the brand aggregation.

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 the resource (brands) and the scope constraint (only brands with active deals) plus the payload (deal counts), which cleanly distinguishes it from siblings like list_models, list_countries, and search_deals. It never uses an explicit verb, relying on the tool name to supply the 'list' action.

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?

'Accepts the same filters as search_deals' implies the intended workflow (facet/count view over the same filtered deal set), but there is no explicit statement of when to pick this over search_deals or list_models, and no exclusions. Usage must be inferred from the filter note.

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