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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior, so the bar is lower. The description adds genuinely new context: the premium paywall, the sibling call needed to get a key, the x402 alternative, and the basis-calculation side effect of spotRefs — none of which appear in structured fields.

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 access/pricing condition is front-loaded in a bracketed tag, followed by purpose, then the optional basis feature, then a short disclaimer. Every sentence carries information; the trailing 'not investment advice' clause is padding but brief.

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, return-value explanation isn't required, and the description covers access model, market scope, filtering by builder dex, and the optional basis computation. The one soft spot is no guidance on how paging behaves or when to raise `limit` toward its 200 max.

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 50%: `dex` and `spotRefs` are described in the schema, while `limit` and `offset` carry only type/default/bounds. The description only elaborates spotRefs marginally ('basis vs an external reference') and says nothing about dex name syntax or pagination, so it neither compensates for the gap nor adds much beyond the schema.

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 — analytics (volume, open interest, funding, 24h change) for HIP-3 builder-deployed perp markets — and scopes it to builder dexs, which differentiates it from generic siblings like hl_get_markets and hl_funding_screener. An agent can tell what this returns without opening the 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?

Gives a concrete prerequisite and access path: needs an API key, obtainable via hl_request_free_key or paid per call through x402, and explains that spotRefs should be passed when basis vs an external reference is wanted. It does not explicitly say when to prefer this over hl_get_markets or hl_funding_screener, so it stops short of full when/when-not guidance.

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