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

Annotations cover readOnly and openWorld, but the description adds meaningful operational context the annotations do not: it is a paid endpoint ($0.01 USDC per call via x402 on Base or Solana) and is signed. Pricing and payment-rail requirements are exactly the kind of behavioral disclosure an agent needs before invoking.

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 payload, then trails with exposure framing and pricing. It is a long single sentence, but every clause maps to a distinct returned field, so little is wasted.

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 carries the burden of explaining return content, and it does so thoroughly (account value, APR, multi-window PnL, per-coin net positions, 24h movers). Minor gap: it does not describe the response shape or freshness of the data.

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?

The tool takes zero parameters, so the baseline of 4 applies; there is no parameter syntax to clarify. The description appropriately spends its budget on output content rather than nonexistent inputs.

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?

Names a specific resource (Hyperliquid's own HLP market-making vault) and enumerates exactly what it reports: account value, APR, PnL over multiple windows, and net position per coin, including most long/short and biggest 24h changes. An agent can immediately tell this apart from price/perp/market siblings.

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 description implies when to reach for it ('shows where the exchange itself is exposed'), but never states when-not to use it or names an alternative sibling. Usage is inferable from the enumerated payload rather than explicit.

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