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

Annotations declare readOnlyHint=false, openWorldHint=true and non-idempotency; the description adds genuinely new behavioral facts: the $0.002 USDC charge per successful call (which explains the non-read-only annotation), the fixed public info endpoint, and the explicit disclaimer that Forest does not trade, sign, or read a wallet. It also clarifies that the annualized field is simple nominal, not compounded or forecast, which prevents misuse of the return value.

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?

Purpose and returned fields are front-loaded in the first sentence, the scope/limits disclaimer follows, and the price lands last where the agent needs it before committing. Dense but no filler; every clause carries information.

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 the returned metrics, and it discloses cost, endpoint scope and data caveats. What is missing is only minor: no indication of error behavior or how a failed/unavailable coin is reported.

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?

Only one parameter ('coin') and schema description coverage is 100%, so the baseline is 3. The description adds no syntax guidance (e.g., Hyperliquid ticker conventions) and only implicitly reinforces that a single coin scopes each call.

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 precise verb ('Return') and resource ('one current Hyperliquid native perpetual snapshot') and enumerates the exact fields returned (hourly funding, 8-hour equivalent, mark/oracle basis, OI, volume, max leverage). The 'Hyperliquid native perpetual' framing cleanly distinguishes it from sibling crypto_spot_price and the other preflight/commerce tools without needing to name them.

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 implied rather than stated: the agent can infer this is the tool for perp funding/mark data, and 'one current snapshot' quietly rules out historical queries or batch lookups. However, there is no explicit when-to-use guidance, no statement of when to prefer it over a sibling, and no mention that multiple coins require multiple calls.

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