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

Annotations already declare readOnlyHint=true / destructiveHint=false, so safety is covered. Beyond that, the description discloses cost and payment rail ('Paid in USDC on Base') and explains the two result shapes (standalone_markets for two-sided markets vs grouped_questions with a 'none of the above' fallback), which is real behavioral context an agent needs before calling.

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 purpose and market coverage are front-loaded, and the routing exclusion is stated early. It is dense but cohesive; the sentence about fields being 'parsed verbatim' and the USDC payment note could be tightened, though both earn their 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 an output schema present, return values need not be explained, and the description instead covers market-type coverage, result-shape semantics, filtering, cost, and sibling exclusions. Complete enough to call correctly; only the absence of an explicit when-to-use trigger keeps 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?

Schema description coverage is 100% and all three parameters are documented in-schema with defaults, ranges and examples. The description only restates that template/underlying filters are optional, adding no new syntax or semantics, so the baseline 3 applies.

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+resource ('Real-time probability snapshot of Hyperliquid's HIP-4 outcome (prediction) markets') and enumerates the market types covered. It also explicitly names the sibling tools it should not be confused with (prediction.neg_risk_arbitrage / prediction.exit_capacity_audit for Polymarket), so an agent can disambiguate 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?

Gives a clear negative routing rule ('Do not use for Polymarket data') with named alternatives, plus guidance that template/underlying filters narrow results. It stops short of an explicit when-to-use trigger for the tool itself, but the covered market types and the exclusion make the selection decision reasonably unambiguous.

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