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

Annotations already declare readOnlyHint=true, openWorldHint=true, destructiveHint=false, so safety is covered. The description adds genuinely useful behavior: prices are market-only (no model output) and the Kalshi fee is included in the cheapest-venue computation, which materially affects interpretation.

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?

Front-loaded with the use-case trigger, then the return shape, in two tight sentences with no filler. The verbatim user-question framing is slightly informal for a spec but earns its place by anchoring intent.

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 carries the burden of describing returns, and it does: cheapest venue per side across named books with fees included. Combined with 100% schema coverage on inputs and read-only annotations, an agent has enough to invoke it correctly; only the exact response row shape is unspecified.

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 every parameter (game, team, limit clamping, player, statType with its four options) is already documented in the schema. The description's mention of points/rebounds/assists/threes only restates the statType enum, adding no syntax or format detail beyond the schema. 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?

Names a specific resource (every Kalshi NBA player-prop strike) and the exact output (the same strike priced beside DraftKings, FanDuel, BetRivers, Fanatics, ESPN, Novig, ProphetX, cheapest venue per side). Clearly distinct from siblings like nfl_prop_board, explain_prop, and best_available.

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 opening quote — "where is LeBron's points line cheapest tonight" — gives a concrete trigger scenario that makes the intended use obvious. However, it states no when-not condition and does not explicitly route the agent to alternatives (e.g. nfl_prop_board for NFL props, explain_prop for explanations).

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