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

Annotations already declare readOnly, non-destructive and open-world, and the description reinforces this with 'Reads or computes only and changes nothing'. It adds meaningful behavior beyond annotations: data is public on-chain info from Hyperliquid's info API read live, cost is $0.01/call with the first 25 free and failed calls free, and repeats are not free (consistent with idempotentHint=false). It stops short of describing latency, rate limits, or behavior when the address has no account.

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-loaded with the payload contents, but the first sentence is an extremely long enumerated list packed with a dozen field names. The payment/pricing material and the 'reads or computes only' disclaimer consume meaningful space, some of which partly restates the readOnly annotation.

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, so the description must carry return-value disclosure itself — and it does, field group by field group, including the parenthetical clarifying that cumulative funding corresponds to Hyperliquid's cumFunding. For a single-parameter read tool, an agent has everything needed to call it 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?

Schema coverage is 100% and there is only one parameter, so the baseline is 3; the description earns an extra point by clarifying that the address may be any Hyperliquid account (a trader, a vault, or an agent's book) and by supplying a concrete example address that demonstrates the expected 0x format.

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 concrete verb+resource (fetch any Hyperliquid account by address) and enumerates exactly what comes back: perp account value, notional, margin used, withdrawable, leverage, unrealized PnL, every open position with side/size/entry/value/PnL/ROE/liquidation price/leverage/cumFunding, spot balances, and up to 50 open orders. This clearly separates it from sibling tools like hyperliquid_market, hyperliquid_prices and hyperliquid_candles, which are market-data rather than account-data endpoints.

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 concrete usage contexts — 'track a trader, a vault or your own agent's book' — and a runnable example with an address. It does not name an alternative or state exclusions (e.g., use hyperliquid_funding_history instead for funding-only queries, or hyperliquid_candles for price series), so routing decisions against siblings are left largely implicit.

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