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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely non-structured behavior: a per-call USDC charge via the x402 payment protocol, which affects whether an agent should call it at all. It also discloses the response contents, which matters because there is no output schema. It stops short of stating failure modes (unknown wallet, non-HL wallet) 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?

Three tight sentences, front-loaded with the resource and its payload, then a use case, then cost. Every sentence carries information; the field enumeration is slightly dense but justified given there is no output schema.

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 compensates by enumerating return fields, and it discloses pricing and the read-only nature. The remaining gap is the wallet parameter's expected format and any error/empty-account behavior, which an agent would need to call this reliably on the first try.

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 0%, so the single wallet parameter is undocumented in structured form. "Any wallet's Hyperliquid perpetuals account" establishes that the parameter identifies the account to query, which is a small but real clarification, yet no address format, chain, or casing requirements are given.

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 resource (a wallet's Hyperliquid perpetuals account) and enumerates exactly what is returned: account value, positions with size/entry/uPnL/leverage/liquidation price, orders, spot balances. This is far more specific than a tautology and lets an agent distinguish it from generic siblings like perps or wallet_portfolio, though it does not name those siblings explicitly.

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?

"Track whales or your own risk" gives a concrete motivating use case, and the stated $0.003 USDC/x402 cost is decision-relevant. However, there is no when-not guidance, no exclusion of the nearby perps or wallet_portfolio tools, and no stated prerequisites (e.g. wallet must be Hyperliquid-active).

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