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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds pricing, the two payment paths (x402 vs prepaid key/pass), and a no-charge-on-failure guarantee. These are genuine behavioral facts not present in the annotations or schema, though return shape and rate/coverage limits are unstated.

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 pricing and coverage facts are front-loaded, which is good, but the sentence 'Timed to CFTC Nov 2026 US stock-perp clearance' is marketing framing that does not help an agent decide or invoke. The dense jargon chain of metrics in the middle also makes the sentence harder to parse than necessary.

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 usefully lists the returned metrics (mark/oracle, 24h change, funding, open interest, volume, taker prints, whale net) and explains payment and failure behavior. Missing only edge-case semantics such as what an omitted symbol or limit returns, which for an all-optional-parameter tool is a minor gap.

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 each parameter already has its own description including the dex enum values and api_key format. The description merely restates the parameter names (symbol, dex, limit, min_usd) and omits api_key, adding no meaning beyond the schema baseline.

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?

Names a specific resource (equity/index/commodity perpetuals on Hyperliquid HIP-3 builder DEXes) and enumerates the returned metrics, so an agent knows exactly what it fetches. It does not explicitly distinguish itself from the sibling free_stock_perps, which weakens differentiation against the most likely alternative.

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 makes the paid nature clear ($0.003 USDC, covered by pass_day/pass_month, no charge on failure), which is real usage context. But it never states when to prefer this over free_stock_perps or perp_funding, leaving the paid-vs-free routing decision to inference.

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