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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered; the description goes further by stating it is free, takes no arguments, and that 'nothing is bought by calling it' despite the presence of x402 purchase endpoints. That last clarification is genuinely useful disambiguation for an agent that might otherwise fear a paid call. It stops short of describing response size or rate limits, which keeps it below a 5.

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?

Cost and read-only status are front-loaded, followed by USE WHEN and NOT WHEN, which is the right ordering for scanning. The long parenthetical enumerating catalog contents is dense and slightly list-like, but every element is informative rather than 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?

There is no output schema, so the description carries the burden of describing returns, and it does so by listing the catalog fields and pointing to the equivalent public JSON endpoint. Combined with the zero-argument schema and full annotations, an agent has everything needed to decide and call. Only minor omissions such as response size or format detail keep it from a 5.

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 zero parameters the baseline is 4, and the description reinforces this by explicitly saying 'No arguments; no payment', removing any doubt about required inputs. There is no further parameter meaning to add.

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 and resource ('returns the catalog of the sealed archive') and enumerates exactly what the catalog contains: coverage, files, SHA-256, sample, offers, x402 endpoints. It also names the sibling tools it is not for (get_liq_radar, get_native_depth), so an agent can separate it from live-data tools without opening any schema.

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?

Explicit 'USE WHEN' clause pins the trigger to historical raw Hyperliquid L2 order-book data for BTC or ETH, and an explicit 'NOT WHEN' clause routes live-market needs to named alternatives. The conditions selecting this tool versus others are fully spelled out rather than inferred.

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