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

Annotations already declare the safe-read profile (readOnly, idempotent, non-destructive, open-world), yet the description adds real value beyond them: an access/cost model (API key or x402 payment), the fact that metrics are derived from vault history, and an explicit 'analytics only, not investment advice' disclaimer. It does not cover rate limits or latency, but with an output schema present the remaining gap is minor.

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 premium/auth banner is correctly front-loaded because it gates invocation, followed by purpose, inputs, and a short disclaimer. It is dense but every clause carries information; only the enumerated metric list is slightly longer than the schema warrants.

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 values need no explanation, and the description supplies the remaining essentials: access path, input source (explicit list vs env var), 50-vault cap context, and the basis of the metrics. An agent has enough to call it correctly on the first attempt.

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 only 33%, so the description should compensate more than it does. It explains the `vaults` input and the HL_VAULT_ADDRESSES fallback, but never mentions `minTvlUsd` or the default `sort` value, and the phrase 'screen by APR, max drawdown, Sharpe/Sortino, age, ... leader capital share' does not map cleanly onto the five sort enum values — age and leader capital share are not sortable options, which risks an agent expecting filter parameters that do not exist.

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 (screen) and resource (Hyperliquid user vaults) plus the dimensions scored: APR, drawdown, Sharpe/Sortino, age, TVL, leader capital share. This clearly separates it from siblings like hl_funding_screener and hl_hip3_analytics without the agent needing to open 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?

The description gives one concrete operational prerequisite — obtain a key via hl_request_free_key or pay per call via x402 — which is genuinely useful before invoking. However, it never says when to pick this over the other screener/analytics siblings (hl_funding_screener, hl_portfolio_risk, hl_hip3_analytics), so selection guidance between alternatives is left implicit.

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