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

With no annotations supplied, the description carries the full burden and does so: it discloses that responses are derived figures only, cached for 60 seconds, that an unknown coin returns 400 before payment (not charged), that unlisted venues are reported as unavailable, and that pricing is $0.002 USDC via x402 on Base or Solana. Payment, error, caching and provenance behavior are all surfaced where structured fields are silent.

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?

The definition is short, front-loaded with the usage trigger, then Input/Output/caveats/example/price in a scannable order, with no wasted sentences. It is written in dense telegraphic fragments and the example and price clauses run together awkwardly, which keeps it from a 5.

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?

There is no output schema, and the description compensates fully by enumerating the returned fields: venues ranked by annualized funding, per-hour and APR normalization, max-min spread with short/long venue, consensus mean, and Hyperliquid mark versus oracle and dYdX oracle basis. Combined with error and pricing behavior, an agent has everything needed to call it correctly and interpret the result.

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?

Only one parameter exists and schema coverage is 100%, so the baseline is 3. The description adds a concrete example ('?coin=BTC') but otherwise restates what the schema already says about unknown or unlisted coins, adding no new meaning beyond format illustration.

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 title and first sentence state a specific action and resource: rank perpetual funding across venues for a single coin, explicitly limited to DEX venues (Hyperliquid, dYdX, GMX, Lighter, Paradex). The cross-venue scope and the '(carry/crowding)' framing distinguish it from Hyperliquid-only siblings such as hl_funding_screener and hl_funding_history without either schema being opened.

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 opening clause gives an explicit trigger condition ('Use when an agent compares perpetual funding across venues for one coin'), which is a real when-to-use statement rather than an implied one. It stops short of naming a competing sibling (e.g. crypto_perp_basis or hl_funding_screener) or stating when to prefer Hyperliquid-only tools, so it lands below a 5.

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