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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, covering the safety profile. The description adds valuable behavioral context beyond annotations: data is 'live from Hyperliquid's public info API' (no auth), there is a cost of '$0.002 per call (10 free/day)', and the funding APR formula is explained ('hourly × 8,760'). No contradiction with annotations.

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 dense sentences with no filler. The first sentence front-loads the data fields and ranking capability, the second clarifies scope and live-source, the third explains the funding formula and pricing. Every sentence carries essential information that an agent needs before calling the tool.

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?

Given the read-only, idempotent annotations and the detailed description, an agent has everything needed to invoke the tool correctly: data fields, filter and sort options, the funding APR calculation, the live API source, and the per-call cost. There is no output schema, but the description enumerates the returned data, so return semantics are adequately covered. Minor omissions like the 'funding_negative' sort value are already present in the schema.

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 only 33% (just the coin field). The description compensates by explaining the coin parameter ('filter to one coin') and the sort parameter ('ranked by volume, OI, funding or movers'). It doesn't explicitly mention the 'funding_negative' enum value or the limit parameter, but the schema itself documents the enum values and the limit min/max/default, so the description adds meaningful meaning where coverage is missing.

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 states a specific resource ('Every Hyperliquid perpetual') and a comprehensive list of returned fields (mark/oracle price, 24h change and volume, open interest, funding APR, premium). It also clearly presents the core behaviors of ranking and filtering, making the tool's purpose unmistakable even without a verb.

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?

The description provides clear context for when to use the tool: whenever Hyperliquid perp market data is needed, 'filter to one coin or rank the whole board.' It does not name sibling alternatives or explicitly state exclusions, but the Hyperliquid-specific scope and the mention of the public info API imply appropriate usage without ambiguity.

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