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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description still adds genuinely useful behavior beyond that: the $0.005 per-call cost, the deterministic sort order ('most traded first'), and the data source (HIP-4). It omits pagination/limit behavior, which keeps 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?

Two sentences, front-loaded with the data source, cost and sort order before the content inventory and the filter hint. The middle clause is dense with a long comma-separated inventory, but every element carries selection-relevant information, so little is wasted.

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 enumerates the returned fields (question, per-option probability, 24h change in points, 24h USDC volume) and coverage areas, so an agent knows what it will receive. Missing details such as result-count behavior for the limit parameter or error modes keep it short of 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%, so the baseline is 3. The description reinforces that filtering is by category or free text and gives example query terms in the schema itself, but it adds no format or constraint detail (e.g., limit cap of 200) beyond what the schema already documents.

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?

The description names a specific resource (open prediction markets on Hyperliquid HIP-4) and enumerates exactly what each row contains: question, option probabilities, 24h point change, 24h USDC volume, plus the covered subject areas. That is far more than a restatement of the name. It stops short of explicitly distinguishing itself from adjacent siblings like macro.fed_odds or decision.pre_trade, which would be needed for a 5.

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?

'Filter by category or text' implies how to narrow results, so usage is partially inferable, but there is no statement of when to reach for this tool versus macro.fed_odds (Fed odds), market.opportunities, or the decision.* tools. No when-not guidance or alternatives are offered.

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