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

Annotations already establish readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely non-structured context: the paid-call model ($0.003 USDC per successful call via x402 on Base/Solana/Arc) and the fact that failed calls are not charged, which affects whether and how an agent should invoke it. It does not cover rate limits or latency.

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?

A single front-loaded paragraph that opens with the action and scope before listing returned fields, the filter, the disclaimer, and the price. Dense but efficient; the returned-field enumeration is partly redundant with the output schema.

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, the description need not explain return values, yet it still summarizes them, and it adds source coverage, the time bound, and the payment terms. An agent has enough to call it correctly; only the routing decision against sibling market tools is under-specified.

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 all three parameters are already documented in the schema; the description only restates the max-30 constraint on days and the optional keyword filter. Per the baseline rule, this is a 3 with no extra syntax or format detail beyond the schema.

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 gives a specific verb and resource ("Fetches recently resolved prediction markets") and names the data sources (Polymarket, Manifold) plus the lookback scope. It stops short of distinguishing itself from close siblings like pm_history, pm_event, or pm_search, so an agent cannot tell from the description alone which one to pick.

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?

Usage is implied by "recently resolved" and the max-30-day window, and the keyword filter is described, but there is no explicit when-to-use/when-not or reference to alternative tools for historical or open (unresolved) markets. The disclaimer and pricing note inform the caller but do not guide tool selection.

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