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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses the return shape (separate perp and outcome-market keys) and hints at a cost dimension ('cheapest way'), but says nothing about auth/payment, rate limits, or error behavior for a tool with three undocumented parameters.

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 tight sentences that front-load the core value proposition and fold the filter example inline without padding. Slightly dense on the outcome-market parenthetical, but every clause carries information.

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 no annotations and no output schema, the description should do more: it covers purpose and output categories well, but two of three parameters remain opaque and there is no guidance on cost/payment despite the x402 naming. Adequate but with clear gaps for a 3-parameter 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 0%, so the description must compensate, and it only explains one of three parameters: filter is documented as case-insensitive substring with a concrete example. limit and includeOutcomes are never mentioned, and the schema's odd string typing for both is left unexplained.

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 gives a specific verb and resource – 'Every Hyperliquid mid price in one call' – and even describes the two payload classes (plain perp coins vs. numbered outcome markets with keys like '#12090'). Scope is distinctive enough to separate it from ticker-scoped siblings, though no sibling is named explicitly.

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 states clear use contexts ('price a whole portfolio or screen the exchange') and implicitly positions itself as the bulk/whole-exchange alternative to narrower lookups. It stops short of naming an explicit alternative or a when-not condition, so it falls just below the top band.

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