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

Annotations declare readOnlyHint and openWorldHint, and the description adds material context beyond them: the metered cost ('$0.003 USDC per call (x402)') and the shape of returned data (hourly series with average and annualised rate; market ranking with open interest and volume). It stops short of noting pagination or rate limits.

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 tightly packed sentences plus a short cost note; the tool's purpose and its two modes are front-loaded before the payoff and pricing details. No filler, though the first sentence is dense enough to need a second read.

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 output schema, the description does the work of explaining return contents (funding series, averages, OI, volume, highest/lowest ranking). The main residual gap is the undefined days/limit parameters and lack of any pagination or result-cap guidance.

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 only 33%: coin carries a description, but days and limit are undocumented in both schema and description. The description implies a time-series window and a ranked result size but never defines what days or limit control, so it only partially compensates for the coverage gap.

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 ('Perpetual funding rates on Hyperliquid') and enumerates both operating modes: single-coin hourly history versus whole-market ranking. An agent can distinguish this from siblings like perps and perps_positions without opening any schema.

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 a concrete use case ('Spot crowded trades and carry opportunities') and the coin-present vs coin-absent selection rule is implied by the mode split. However, it names no alternative tool and states no when-not-to-use condition.

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