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

Beyond the readOnlyHint/openWorldHint annotations, it discloses the commercial model that materially affects invocation: $0.003 USDC per successful call, paid via x402 on Base, Solana, or Arc, and failed calls are not charged. It also volunteers the key limitation of the underlying data source, which prevents the agent from over-trusting the output.

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 sentences, front-loaded with the returned data, then the estimation caveat, then pricing. The first sentence is a long run-on list of fields, but every clause carries information the agent needs; nothing is redundant.

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 an output schema present and annotations covering the safety profile, the remaining gaps an agent would care about are payment/auth mechanics and output reliability, and the description addresses both. A caller has everything needed to decide and to invoke correctly.

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 single 'coin' parameter is fully documented in the schema itself (100% coverage, with the same BTC/ETH/SOL examples), so the description adds no new meaning beyond restating that the tool is per-perpetual. Baseline 3 is appropriate when the schema does the work.

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 a specific verb and resource ('For one perpetual on Hyperliquid') and enumerates exactly what is returned: mark price, open interest in coins and USD, funding rate, and liquidation estimates at 5x/10x/20x/50x. That scope is distinct from the nearest sibling, agent_intel_perp_funding_rate_heatmap, which is a cross-market view rather than a single-coin snapshot.

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 establishes the context clearly ('public info API', one perp at a time) and adds an important usage caveat: the liquidation levels are formula-based estimates, not observed positions, because the API does not expose per-trader liquidation prices. It does not name an alternative tool or list what to use when the estimates are insufficient, which keeps it from a 5.

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