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

Annotations already cover read-only and non-destructive status, but the description adds substantive behavior the annotations cannot express: the data comes from Hyperliquid's public API, the call costs $0.002 via x402 USDC or a card key with the first 25 free and failed calls free, and repeats are charged (which explains the non-idempotent hint in practical terms). 'Reads or computes only and changes nothing' reinforces the safety profile, and the cost/rate detail is exactly the operational context an agent needs before retrying.

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 field enumeration is front-loaded and dense with information, and the default behavior follows immediately. The closing sentence on pricing and read-only behavior is long and partly duplicates the readOnlyHint annotation, but the cost terms are genuinely load-bearing and worth the space.

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?

For a single-parameter read tool with no output schema, the description effectively doubles as a return-value contract by listing every metric and its units (coins and USD, hourly funding, APR). Payment mechanics and the no-coin default are covered; only minor gaps remain, such as response shape for the multi-market default case or handling of unknown symbols.

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?

With a single optional parameter at 100% schema description coverage, the schema already defines the coin symbol and its default. The description restates example symbols and the default market list, adding only the illustrative 'Example: coin=BTC' beyond the schema, so it sits at the baseline rather than adding new semantic depth (e.g., case sensitivity or unsupported-symbol behavior).

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 description names the exact resource (live Hyperliquid perpetual futures data for a coin) and enumerates the returned metrics: mark/oracle/mid price, hourly funding and APR, premium, open interest in coins and USD, 24h volume and price change, max leverage. It also states the no-argument default (20 most traded markets by 24h volume), which separates it behaviorally from history-oriented siblings. It never names hyperliquid_prices, hyperliquid_funding_history, or hyperliquid_orderbook explicitly, so the agent must infer the snapshot-vs-history distinction from the word 'Live'.

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?

It gives concrete use cases ('funding-rate checks, basis trades, derivatives dashboards and market context') and a worked invocation ('Example: coin=BTC'), plus the implicit when-to-use signal of omitting the coin for a market-wide leaderboard. There are no explicit exclusions or named alternatives, so an agent has clear context but no routing rules against the sibling Hyperliquid tools.

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