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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds operational context the annotations cannot: a 5-minute refresh cadence, explicit 503 behavior on stale data, and a per-call cost of 0.02 USDC with the accepted payment chains. Cost and failure semantics are exactly the kind of behavioral disclosure that saves an agent from a failed call.

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?

Four tight sentences with the trigger condition front-loaded, then return shape, then the coin variant, then the operational constraints (refresh, staleness, price). No sentence is filler despite the density of 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?

For a two-parameter, open-world, paid read tool with an output schema, the description covers trigger, aggregation semantics, the coin drill-down, freshness, failure mode, and pricing — leaving no ambiguity about whether or how to call 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% and both parameters are already documented in the schema, including the 1-50 bound and default for top. The description restates that coin adds liquidation bands and top positions without adding format, default, or interaction detail beyond the schema, so 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 verb and resource — returning open perp positions of the largest Hyperliquid accounts aggregated per coin — and enumerates the exact aggregates produced (net long/short USD, account counts, size-weighted entries, liquidation distance, uPnL). This is clearly distinguishable from siblings like get_positioning or get_perp because it is explicitly whale-scoped and per-coin aggregated.

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?

"Use when an agent needs to know how the biggest Hyperliquid traders are positioned" gives a clear triggering condition, and the coin=BTC sentence shows the drill-down mode. It does not name a competing sibling or state when not to use it, so it stops short of the 5 rubric.

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