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

Goes well beyond annotations (readOnly/idempotent/openWorld): discloses pricing and x402 payment flow, the free-tier quota, that errors return isError without charge, that funding is hourly with apr = hourly × 8,760, and that data is live from the public info API — all operationally important context.

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?

Front-loads the resource and its metrics, then layers ranking, filtering, pricing and error behavior — every element earns its place, though the density of pricing/error clauses makes it slightly heavy for one paragraph.

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 values needn't be explained; the description still covers cost, errors, funding conventions and both usage modes, leaving no material gap for an agent to call it correctly.

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%, so the schema already documents coin, sort enum and limit. The description adds only marginal interpretation (rank vs filter, movers), which is the baseline case when the schema does the heavy lifting.

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 a specific verb+resource (every Hyperliquid perpetual with mark/oracle price, 24h change, volume, OI, funding APR, premium) and distinguishes itself from siblings like funding_rates, cex_ticker and crypto_price by anchoring to Hyperliquid's perp board.

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?

Gives clear usage context — 'Filter to one coin or rank the whole board' — and explains the rank modes. It stops short of naming an alternative tool or a when-not-to-use condition, so it lacks the explicit routing a 5 requires.

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