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

With no annotations, the description carries the full burden and discharges a meaningful part of it: it discloses a $0.01 per-call cost drawn from shop credits and that failed/empty calls are free, plus a facts-only disclaimer. It omits rate limits, key/auth details beyond 'get a key', and any pagination behavior.

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 what-it-returns sentence is front-loaded, followed by a short disclaimer and a compact pricing note; each block carries information. The pricing/disclaimer sentences are slightly promotional but earn their place by covering cost behavior.

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?

Without an output schema the description does the work of listing return fields, and without annotations it covers cost and failure behavior. It is nearly complete for a no-required-param read tool, though freshness semantics of the 24h/7d window and pagination remain unstated.

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 (q, limit, window) are documented in the schema, so the baseline is 3. The prose adds no syntax or format guidance beyond what the schema already provides.

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 states a specific resource (prediction markets that just settled) scoped to two named venues (Polymarket AND Kalshi) and enumerates the returned fields (outcome, last price before close, volume, closed_at). This lets an agent distinguish it from closing-soon siblings like pm_closing without opening a 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?

It gives a target audience and context ('for forecasting agents grading themselves') and mentions buy_credits for obtaining a key, but it never names an alternative tool or states when to prefer pm_closing/pm_odds instead. Usage is implied rather than routed explicitly.

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