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

Annotations already declare this a safe, read-only, idempotent, closed-world operation, so the safety profile is covered. The description adds genuinely non-obvious behavioral detail that annotations cannot express: first-purchase offers, coupons and upper bounds are excluded, providers with a Concerning sourcing check are dropped, and a market median is included in the result — these materially affect how an agent should interpret the output.

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 core claim (lowest regular checkout prices, ranked) is front-loaded, and the methodology clauses that follow are load-bearing rather than filler. The single long sentence carrying all the exclusion rules is dense, but trimming it would lose information an agent needs to trust the ranking.

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?

With an output schema present, return shape need not be explained, and annotations cover the safety profile. What remains — pricing basis, exclusion rules, and the median that appears in results — is fully stated, leaving no material gap for a zero-required-parameter read-only tool.

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 100%, so every parameter (limit, needs, basketGb) is already documented with ranges, enums and per-value meaning. The description only restates the 1/10/100 GB options and the existence of a requirements filter, adding no syntax or interaction detail beyond the schema — the baseline 3 applies.

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 a specific resource (regular checkout prices for 1/10/100 GB of residential proxy traffic) and an explicit ranking methodology, so an agent knows exactly what comes back: a price ranking, not a provider catalog. It does not, however, contrast itself with siblings like compare_providers or find_providers, which plausibly return ranked or filtered provider lists, so the sibling distinction is left to inference.

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?

'Optionally only providers meeting given requirements' implies the use case (find the cheapest option subject to hard constraints), which is more than nothing. But there is no explicit when-to-use/when-not statement and no alternative tool is named, even though find_providers and compare_providers overlap heavily with a filtered ranking.

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