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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds value by naming the returned data points (mark, oracle, funding, OI, volume, max leverage), but says nothing about behavior for an unknown/non-listed coin (error vs empty) or data freshness.

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?

One dense sentence, front-loaded with what the tool returns for which key, and the field list is exactly the information an agent needs. No filler.

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 return-shape burden and does so by enumerating fields. The remaining gap is edge-case behavior (unknown coin, stale quotes) and no pointer to the sibling listing tool.

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 0% — the single 'coin' parameter has no description or format constraint — so the description must compensate. It does so usefully with concrete examples (BTC, ETH, HYPE), disambiguating the bare symbol from a pair like 'BTC-PERP' or an asset index.

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+scope: a single Hyperliquid perpetual market looked up by coin, and enumerates the fields returned. The plural sibling perps_markets is implicitly contrasted by 'One ... market by coin', but it is never named, so the differentiation is inferential rather than explicit.

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?

Usage is only implied: an agent can infer this is for single-market lookup versus the listing tool, but there is no explicit 'use this when' or 'use perps_markets instead when'. No prerequisites or exclusions are stated.

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