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

Annotations already declare readOnly, idempotent, openWorld and non-destructive. The description adds real context beyond them: an auth requirement (Carry Oracle key, US$100/month), the factual 'data, not a signal' framing, and the returned fields. Return format details (pagination, refresh cadence) remain unstated, keeping it from 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?

Three tight sentences, front-loaded with scope and contents, then the cost/auth caveat, then the routing rule. Every sentence earns its place.

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 naming the returned fields (funding, OI, 24h volume, spot mark) and the access requirement. An agent has enough to decide and call 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?

Schema coverage is 100%, so both dex and min_vol are fully documented in the schema. The description implies dex filtering ('every dex', 'filter to one dex' lives in schema) but adds no syntax or default detail beyond it, so baseline 3 is correct.

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 resource (annualised funding) and scope (every perp on every Hyperliquid dex: main + HIP-3), with a clear verb-like framing. It separates itself from price_for and carry_history explicitly, so an agent can route without opening schemas.

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 when-to-use ('ALL perps on ALL Hyperliquid dexes at once') and names the alternatives for the narrower case ('for one coin use price_for or carry_history'). Nothing is left to inference.

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