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

With no annotations, the description carries the full burden and does disclose important traits: it is derived analytics (not raw quotes), it is a paid x402 endpoint at $0.05, and it names the returned fields (direction, liquidity, per-venue calibration). It omits freshness/delay handling and pagination behavior, which keeps it short of 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?

Purpose is front-loaded in the first clause, and the HTTP/price/docs footer is compact and useful. The middle sentence is long and dash-laden, but every element (direction, liquidity, calibration) maps to actual output content, 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 sensibly enumerates the returned fields and discloses the payment model and docs URL. Combined with full schema coverage of the two params, an agent has nearly everything needed; only pagination and data-freshness semantics are missing.

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?

Both parameters (min_gap, category) are fully documented in the schema at 100% coverage, so the schema does the heavy lifting. The description only indirectly touches the gap concept via 'ranked by gap' and adds no syntax or unit detail beyond the schema's own descriptions.

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 precise verb+resource: active markets priced on both Kalshi and Polymarket, ranked by implied-probability gap. An agent can tell this is a cross-venue disagreement/arbitrage scan rather than a single-venue quote, but the description never explicitly differentiates itself from near siblings like probability_odds-compare, probability_venue-calibration, or the -delayed variant.

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 use case is implied (surface where two venues diverge), and the trailing note that the calibration claim is 'audited by the free scorecard' hints at a follow-up call. However, there is no explicit when-to-use, when-not-to-use, or routing against the similar odds-compare/venue-calibration siblings.

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